This series backports the patchset "exit: Put an upper limit on how often we can oops" (https://lore.kernel.org/linux-mm/20221117233838.give.484-kees@kernel.org/T/#...) to 5.15, as recommended at https://googleprojectzero.blogspot.com/2023/01/exploiting-null-dereferences-...
This required backporting various prerequisite patches.
I've tested that oops_limit and warn_limit work correctly on x86_64.
Eric W. Biederman (2): exit: Add and use make_task_dead. objtool: Add a missing comma to avoid string concatenation
Jann Horn (1): exit: Put an upper limit on how often we can oops
Kees Cook (8): panic: Separate sysctl logic from CONFIG_SMP exit: Expose "oops_count" to sysfs exit: Allow oops_limit to be disabled panic: Consolidate open-coded panic_on_warn checks panic: Introduce warn_limit panic: Expose "warn_count" to sysfs docs: Fix path paste-o for /sys/kernel/warn_count exit: Use READ_ONCE() for all oops/warn limit reads
Nathan Chancellor (3): hexagon: Fix function name in die() h8300: Fix build errors from do_exit() to make_task_dead() transition csky: Fix function name in csky_alignment() and die()
Randy Dunlap (1): ia64: make IA64_MCA_RECOVERY bool instead of tristate
Tiezhu Yang (3): panic: unset panic_on_warn inside panic() ubsan: no need to unset panic_on_warn in ubsan_epilogue() kasan: no need to unset panic_on_warn in end_report()
Xiaoming Ni (1): sysctl: add a new register_sysctl_init() interface
tangmeng (1): kernel/panic: move panic sysctls to its own file
.../ABI/testing/sysfs-kernel-oops_count | 6 ++ .../ABI/testing/sysfs-kernel-warn_count | 6 ++ Documentation/admin-guide/sysctl/kernel.rst | 19 ++++ arch/alpha/kernel/traps.c | 6 +- arch/alpha/mm/fault.c | 2 +- arch/arm/kernel/traps.c | 2 +- arch/arm/mm/fault.c | 2 +- arch/arm64/kernel/traps.c | 2 +- arch/arm64/mm/fault.c | 2 +- arch/csky/abiv1/alignment.c | 2 +- arch/csky/kernel/traps.c | 2 +- arch/csky/mm/fault.c | 2 +- arch/h8300/kernel/traps.c | 3 +- arch/h8300/mm/fault.c | 2 +- arch/hexagon/kernel/traps.c | 2 +- arch/ia64/Kconfig | 2 +- arch/ia64/kernel/mca_drv.c | 2 +- arch/ia64/kernel/traps.c | 2 +- arch/ia64/mm/fault.c | 2 +- arch/m68k/kernel/traps.c | 2 +- arch/m68k/mm/fault.c | 2 +- arch/microblaze/kernel/exceptions.c | 4 +- arch/mips/kernel/traps.c | 2 +- arch/nds32/kernel/fpu.c | 2 +- arch/nds32/kernel/traps.c | 8 +- arch/nios2/kernel/traps.c | 4 +- arch/openrisc/kernel/traps.c | 2 +- arch/parisc/kernel/traps.c | 2 +- arch/powerpc/kernel/traps.c | 8 +- arch/riscv/kernel/traps.c | 2 +- arch/riscv/mm/fault.c | 2 +- arch/s390/kernel/dumpstack.c | 2 +- arch/s390/kernel/nmi.c | 2 +- arch/sh/kernel/traps.c | 2 +- arch/sparc/kernel/traps_32.c | 4 +- arch/sparc/kernel/traps_64.c | 4 +- arch/x86/entry/entry_32.S | 6 +- arch/x86/entry/entry_64.S | 6 +- arch/x86/kernel/dumpstack.c | 4 +- arch/xtensa/kernel/traps.c | 2 +- fs/proc/proc_sysctl.c | 33 +++++++ include/linux/panic.h | 7 +- include/linux/sched/task.h | 1 + include/linux/sysctl.h | 3 + kernel/exit.c | 72 +++++++++++++++ kernel/kcsan/report.c | 3 +- kernel/panic.c | 90 ++++++++++++++++--- kernel/sched/core.c | 3 +- kernel/sysctl.c | 11 --- lib/ubsan.c | 11 +-- mm/kasan/report.c | 12 +-- mm/kfence/report.c | 3 +- tools/objtool/check.c | 3 +- 53 files changed, 281 insertions(+), 111 deletions(-) create mode 100644 Documentation/ABI/testing/sysfs-kernel-oops_count create mode 100644 Documentation/ABI/testing/sysfs-kernel-warn_count
base-commit: aabd5ba7e9b03e9a211a4842ab4a93d46f684d2c
From: Xiaoming Ni nixiaoming@huawei.com
commit 3ddd9a808cee7284931312f2f3e854c9617f44b2 upstream.
Patch series "sysctl: first set of kernel/sysctl cleanups", v2.
Finally had time to respin the series of the work we had started last year on cleaning up the kernel/sysct.c kitchen sink. People keeps stuffing their sysctls in that file and this creates a maintenance burden. So this effort is aimed at placing sysctls where they actually belong.
I'm going to split patches up into series as there is quite a bit of work.
This first set adds register_sysctl_init() for uses of registerting a sysctl on the init path, adds const where missing to a few places, generalizes common values so to be more easy to share, and starts the move of a few kernel/sysctl.c out where they belong.
The majority of rework on v2 in this first patch set is 0-day fixes. Eric Biederman's feedback is later addressed in subsequent patch sets.
I'll only post the first two patch sets for now. We can address the rest once the first two patch sets get completely reviewed / Acked.
This patch (of 9):
The kernel/sysctl.c is a kitchen sink where everyone leaves their dirty dishes, this makes it very difficult to maintain.
To help with this maintenance let's start by moving sysctls to places where they actually belong. The proc sysctl maintainers do not want to know what sysctl knobs you wish to add for your own piece of code, we just care about the core logic.
Today though folks heavily rely on tables on kernel/sysctl.c so they can easily just extend this table with their needed sysctls. In order to help users move their sysctls out we need to provide a helper which can be used during code initialization.
We special-case the initialization use of register_sysctl() since it *is* safe to fail, given all that sysctls do is provide a dynamic interface to query or modify at runtime an existing variable. So the use case of register_sysctl() on init should *not* stop if the sysctls don't end up getting registered. It would be counter productive to stop boot if a simple sysctl registration failed.
Provide a helper for init then, and document the recommended init levels to use for callers of this routine. We will later use this in subsequent patches to start slimming down kernel/sysctl.c tables and moving sysctl registration to the code which actually needs these sysctls.
[mcgrof@kernel.org: major commit log and documentation rephrasing also moved to fs/proc/proc_sysctl.c ]
Link: https://lkml.kernel.org/r/20211123202347.818157-1-mcgrof@kernel.org Link: https://lkml.kernel.org/r/20211123202347.818157-2-mcgrof@kernel.org Signed-off-by: Xiaoming Ni nixiaoming@huawei.com Signed-off-by: Luis Chamberlain mcgrof@kernel.org Reviewed-by: Kees Cook keescook@chromium.org Cc: Iurii Zaikin yzaikin@google.com Cc: "Eric W. Biederman" ebiederm@xmission.com Cc: Peter Zijlstra peterz@infradead.org Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: Paul Turner pjt@google.com Cc: Andy Shevchenko andriy.shevchenko@linux.intel.com Cc: Sebastian Reichel sre@kernel.org Cc: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp Cc: Petr Mladek pmladek@suse.com Cc: Sergey Senozhatsky senozhatsky@chromium.org Cc: Qing Wang wangqing@vivo.com Cc: Benjamin LaHaise bcrl@kvack.org Cc: Al Viro viro@zeniv.linux.org.uk Cc: Jan Kara jack@suse.cz Cc: Amir Goldstein amir73il@gmail.com Cc: Stephen Kitt steve@sk2.org Cc: Antti Palosaari crope@iki.fi Cc: Arnd Bergmann arnd@arndb.de Cc: Benjamin Herrenschmidt benh@kernel.crashing.org Cc: Clemens Ladisch clemens@ladisch.de Cc: David Airlie airlied@linux.ie Cc: Jani Nikula jani.nikula@linux.intel.com Cc: Joel Becker jlbec@evilplan.org Cc: Joonas Lahtinen joonas.lahtinen@linux.intel.com Cc: Joseph Qi joseph.qi@linux.alibaba.com Cc: Julia Lawall julia.lawall@inria.fr Cc: Lukas Middendorf kernel@tuxforce.de Cc: Mark Fasheh mark@fasheh.com Cc: Phillip Potter phil@philpotter.co.uk Cc: Rodrigo Vivi rodrigo.vivi@intel.com Cc: Douglas Gilbert dgilbert@interlog.com Cc: James E.J. Bottomley jejb@linux.ibm.com Cc: Jani Nikula jani.nikula@intel.com Cc: John Ogness john.ogness@linutronix.de Cc: Martin K. Petersen martin.petersen@oracle.com Cc: "Rafael J. Wysocki" rafael@kernel.org Cc: Steven Rostedt (VMware) rostedt@goodmis.org Cc: Suren Baghdasaryan surenb@google.com Cc: "Theodore Ts'o" tytso@mit.edu Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Eric Biggers ebiggers@google.com --- fs/proc/proc_sysctl.c | 33 +++++++++++++++++++++++++++++++++ include/linux/sysctl.h | 3 +++ 2 files changed, 36 insertions(+)
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c index 013fc5931bc37..0b7a00ed6c49b 100644 --- a/fs/proc/proc_sysctl.c +++ b/fs/proc/proc_sysctl.c @@ -16,6 +16,7 @@ #include <linux/module.h> #include <linux/bpf-cgroup.h> #include <linux/mount.h> +#include <linux/kmemleak.h> #include "internal.h"
static const struct dentry_operations proc_sys_dentry_operations; @@ -1384,6 +1385,38 @@ struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *tab } EXPORT_SYMBOL(register_sysctl);
+/** + * __register_sysctl_init() - register sysctl table to path + * @path: path name for sysctl base + * @table: This is the sysctl table that needs to be registered to the path + * @table_name: The name of sysctl table, only used for log printing when + * registration fails + * + * The sysctl interface is used by userspace to query or modify at runtime + * a predefined value set on a variable. These variables however have default + * values pre-set. Code which depends on these variables will always work even + * if register_sysctl() fails. If register_sysctl() fails you'd just loose the + * ability to query or modify the sysctls dynamically at run time. Chances of + * register_sysctl() failing on init are extremely low, and so for both reasons + * this function does not return any error as it is used by initialization code. + * + * Context: Can only be called after your respective sysctl base path has been + * registered. So for instance, most base directories are registered early on + * init before init levels are processed through proc_sys_init() and + * sysctl_init(). + */ +void __init __register_sysctl_init(const char *path, struct ctl_table *table, + const char *table_name) +{ + struct ctl_table_header *hdr = register_sysctl(path, table); + + if (unlikely(!hdr)) { + pr_err("failed when register_sysctl %s to %s\n", table_name, path); + return; + } + kmemleak_not_leak(hdr); +} + static char *append_path(const char *path, char *pos, const char *name) { int namelen; diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h index fa372b4c23132..47cf70c8eb93c 100644 --- a/include/linux/sysctl.h +++ b/include/linux/sysctl.h @@ -206,6 +206,9 @@ struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path, void unregister_sysctl_table(struct ctl_table_header * table);
extern int sysctl_init(void); +extern void __register_sysctl_init(const char *path, struct ctl_table *table, + const char *table_name); +#define register_sysctl_init(path, table) __register_sysctl_init(path, table, #table) void do_sysctl_args(void);
extern int pwrsw_enabled;
From: tangmeng tangmeng@uniontech.com
commit 9df918698408fd914493aba0b7858fef50eba63a upstream.
kernel/sysctl.c is a kitchen sink where everyone leaves their dirty dishes, this makes it very difficult to maintain.
To help with this maintenance let's start by moving sysctls to places where they actually belong. The proc sysctl maintainers do not want to know what sysctl knobs you wish to add for your own piece of code, we just care about the core logic.
All filesystem syctls now get reviewed by fs folks. This commit follows the commit of fs, move the oops_all_cpu_backtrace sysctl to its own file, kernel/panic.c.
Signed-off-by: tangmeng tangmeng@uniontech.com Signed-off-by: Luis Chamberlain mcgrof@kernel.org Signed-off-by: Eric Biggers ebiggers@google.com --- include/linux/panic.h | 6 ------ kernel/panic.c | 26 +++++++++++++++++++++++++- kernel/sysctl.c | 11 ----------- 3 files changed, 25 insertions(+), 18 deletions(-)
diff --git a/include/linux/panic.h b/include/linux/panic.h index f5844908a089e..e71161da69c4b 100644 --- a/include/linux/panic.h +++ b/include/linux/panic.h @@ -15,12 +15,6 @@ extern void oops_enter(void); extern void oops_exit(void); extern bool oops_may_print(void);
-#ifdef CONFIG_SMP -extern unsigned int sysctl_oops_all_cpu_backtrace; -#else -#define sysctl_oops_all_cpu_backtrace 0 -#endif /* CONFIG_SMP */ - extern int panic_timeout; extern unsigned long panic_print; extern int panic_on_oops; diff --git a/kernel/panic.c b/kernel/panic.c index cefd7d82366fb..5ee281b996f9e 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -42,7 +42,9 @@ * Should we dump all CPUs backtraces in an oops event? * Defaults to 0, can be changed via sysctl. */ -unsigned int __read_mostly sysctl_oops_all_cpu_backtrace; +static unsigned int __read_mostly sysctl_oops_all_cpu_backtrace; +#else +#define sysctl_oops_all_cpu_backtrace 0 #endif /* CONFIG_SMP */
int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE; @@ -71,6 +73,28 @@ ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
EXPORT_SYMBOL(panic_notifier_list);
+#if defined(CONFIG_SMP) && defined(CONFIG_SYSCTL) +static struct ctl_table kern_panic_table[] = { + { + .procname = "oops_all_cpu_backtrace", + .data = &sysctl_oops_all_cpu_backtrace, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_ONE, + }, + { } +}; + +static __init int kernel_panic_sysctls_init(void) +{ + register_sysctl_init("kernel", kern_panic_table); + return 0; +} +late_initcall(kernel_panic_sysctls_init); +#endif + static long no_blink(int state) { return 0; diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 34ce5953dbb09..928798f89ca1d 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -2220,17 +2220,6 @@ static struct ctl_table kern_table[] = { .proc_handler = proc_dointvec, }, #endif -#ifdef CONFIG_SMP - { - .procname = "oops_all_cpu_backtrace", - .data = &sysctl_oops_all_cpu_backtrace, - .maxlen = sizeof(int), - .mode = 0644, - .proc_handler = proc_dointvec_minmax, - .extra1 = SYSCTL_ZERO, - .extra2 = SYSCTL_ONE, - }, -#endif /* CONFIG_SMP */ { .procname = "pid_max", .data = &pid_max,
From: Tiezhu Yang yangtiezhu@loongson.cn
commit 1a2383e8b84c0451fd9b1eec3b9aab16f30b597c upstream.
In the current code, the following three places need to unset panic_on_warn before calling panic() to avoid recursive panics:
kernel/kcsan/report.c: print_report() kernel/sched/core.c: __schedule_bug() mm/kfence/report.c: kfence_report_error()
In order to avoid copy-pasting "panic_on_warn = 0" all over the places, it is better to move it inside panic() and then remove it from the other places.
Link: https://lkml.kernel.org/r/1644324666-15947-4-git-send-email-yangtiezhu@loong... Signed-off-by: Tiezhu Yang yangtiezhu@loongson.cn Reviewed-by: Marco Elver elver@google.com Cc: Andrey Ryabinin ryabinin.a.a@gmail.com Cc: Baoquan He bhe@redhat.com Cc: Jonathan Corbet corbet@lwn.net Cc: Xuefeng Li lixuefeng@loongson.cn Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Eric Biggers ebiggers@google.com --- kernel/panic.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-)
diff --git a/kernel/panic.c b/kernel/panic.c index 5ee281b996f9e..5ed1ad06f9a34 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -208,6 +208,16 @@ void panic(const char *fmt, ...) int old_cpu, this_cpu; bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers;
+ if (panic_on_warn) { + /* + * This thread may hit another WARN() in the panic path. + * Resetting this prevents additional WARN() from panicking the + * system on this thread. Other threads are blocked by the + * panic_mutex in panic(). + */ + panic_on_warn = 0; + } + /* * Disable local interrupts. This will prevent panic_smp_self_stop * from deadlocking the first cpu that invokes the panic, since @@ -616,16 +626,8 @@ void __warn(const char *file, int line, void *caller, unsigned taint, if (regs) show_regs(regs);
- if (panic_on_warn) { - /* - * This thread may hit another WARN() in the panic path. - * Resetting this prevents additional WARN() from panicking the - * system on this thread. Other threads are blocked by the - * panic_mutex in panic(). - */ - panic_on_warn = 0; + if (panic_on_warn) panic("panic_on_warn set ...\n"); - }
if (!regs) dump_stack();
From: Tiezhu Yang yangtiezhu@loongson.cn
commit d83ce027a54068fabb70d2c252e1ce2da86784a4 upstream.
panic_on_warn is unset inside panic(), so no need to unset it before calling panic() in ubsan_epilogue().
Link: https://lkml.kernel.org/r/1644324666-15947-5-git-send-email-yangtiezhu@loong... Signed-off-by: Tiezhu Yang yangtiezhu@loongson.cn Reviewed-by: Marco Elver elver@google.com Cc: Andrey Ryabinin ryabinin.a.a@gmail.com Cc: Baoquan He bhe@redhat.com Cc: Jonathan Corbet corbet@lwn.net Cc: Xuefeng Li lixuefeng@loongson.cn Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Eric Biggers ebiggers@google.com --- lib/ubsan.c | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-)
diff --git a/lib/ubsan.c b/lib/ubsan.c index bdc380ff5d5c7..36bd75e334263 100644 --- a/lib/ubsan.c +++ b/lib/ubsan.c @@ -154,16 +154,8 @@ static void ubsan_epilogue(void)
current->in_ubsan--;
- if (panic_on_warn) { - /* - * This thread may hit another WARN() in the panic path. - * Resetting this prevents additional WARN() from panicking the - * system on this thread. Other threads are blocked by the - * panic_mutex in panic(). - */ - panic_on_warn = 0; + if (panic_on_warn) panic("panic_on_warn set ...\n"); - } }
void __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs)
From: Tiezhu Yang yangtiezhu@loongson.cn
commit e7ce7500375a63348e1d3a703c8d5003cbe3fea6 upstream.
panic_on_warn is unset inside panic(), so no need to unset it before calling panic() in end_report().
Link: https://lkml.kernel.org/r/1644324666-15947-6-git-send-email-yangtiezhu@loong... Signed-off-by: Tiezhu Yang yangtiezhu@loongson.cn Reviewed-by: Marco Elver elver@google.com Cc: Andrey Ryabinin ryabinin.a.a@gmail.com Cc: Baoquan He bhe@redhat.com Cc: Jonathan Corbet corbet@lwn.net Cc: Xuefeng Li lixuefeng@loongson.cn Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Eric Biggers ebiggers@google.com --- mm/kasan/report.c | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-)
diff --git a/mm/kasan/report.c b/mm/kasan/report.c index 884a950c70265..bf17704b302fc 100644 --- a/mm/kasan/report.c +++ b/mm/kasan/report.c @@ -117,16 +117,8 @@ static void end_report(unsigned long *flags, unsigned long addr) pr_err("==================================================================\n"); add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); spin_unlock_irqrestore(&report_lock, *flags); - if (panic_on_warn && !test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags)) { - /* - * This thread may hit another WARN() in the panic path. - * Resetting this prevents additional WARN() from panicking the - * system on this thread. Other threads are blocked by the - * panic_mutex in panic(). - */ - panic_on_warn = 0; + if (panic_on_warn && !test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags)) panic("panic_on_warn set ...\n"); - } if (kasan_arg_fault == KASAN_ARG_FAULT_PANIC) panic("kasan.fault=panic set ...\n"); kasan_enable_current();
From: "Eric W. Biederman" ebiederm@xmission.com
commit 0e25498f8cd43c1b5aa327f373dd094e9a006da7 upstream.
There are two big uses of do_exit. The first is it's design use to be the guts of the exit(2) system call. The second use is to terminate a task after something catastrophic has happened like a NULL pointer in kernel code.
Add a function make_task_dead that is initialy exactly the same as do_exit to cover the cases where do_exit is called to handle catastrophic failure. In time this can probably be reduced to just a light wrapper around do_task_dead. For now keep it exactly the same so that there will be no behavioral differences introducing this new concept.
Replace all of the uses of do_exit that use it for catastraphic task cleanup with make_task_dead to make it clear what the code is doing.
As part of this rename rewind_stack_do_exit rewind_stack_and_make_dead.
Signed-off-by: "Eric W. Biederman" ebiederm@xmission.com Signed-off-by: Eric Biggers ebiggers@google.com --- arch/alpha/kernel/traps.c | 6 +++--- arch/alpha/mm/fault.c | 2 +- arch/arm/kernel/traps.c | 2 +- arch/arm/mm/fault.c | 2 +- arch/arm64/kernel/traps.c | 2 +- arch/arm64/mm/fault.c | 2 +- arch/csky/abiv1/alignment.c | 2 +- arch/csky/kernel/traps.c | 2 +- arch/csky/mm/fault.c | 2 +- arch/h8300/kernel/traps.c | 2 +- arch/h8300/mm/fault.c | 2 +- arch/hexagon/kernel/traps.c | 2 +- arch/ia64/kernel/mca_drv.c | 2 +- arch/ia64/kernel/traps.c | 2 +- arch/ia64/mm/fault.c | 2 +- arch/m68k/kernel/traps.c | 2 +- arch/m68k/mm/fault.c | 2 +- arch/microblaze/kernel/exceptions.c | 4 ++-- arch/mips/kernel/traps.c | 2 +- arch/nds32/kernel/fpu.c | 2 +- arch/nds32/kernel/traps.c | 8 ++++---- arch/nios2/kernel/traps.c | 4 ++-- arch/openrisc/kernel/traps.c | 2 +- arch/parisc/kernel/traps.c | 2 +- arch/powerpc/kernel/traps.c | 8 ++++---- arch/riscv/kernel/traps.c | 2 +- arch/riscv/mm/fault.c | 2 +- arch/s390/kernel/dumpstack.c | 2 +- arch/s390/kernel/nmi.c | 2 +- arch/sh/kernel/traps.c | 2 +- arch/sparc/kernel/traps_32.c | 4 +--- arch/sparc/kernel/traps_64.c | 4 +--- arch/x86/entry/entry_32.S | 6 +++--- arch/x86/entry/entry_64.S | 6 +++--- arch/x86/kernel/dumpstack.c | 4 ++-- arch/xtensa/kernel/traps.c | 2 +- include/linux/sched/task.h | 1 + kernel/exit.c | 9 +++++++++ tools/objtool/check.c | 3 ++- 39 files changed, 63 insertions(+), 56 deletions(-)
diff --git a/arch/alpha/kernel/traps.c b/arch/alpha/kernel/traps.c index e805106409f76..f5ba12adde67c 100644 --- a/arch/alpha/kernel/traps.c +++ b/arch/alpha/kernel/traps.c @@ -192,7 +192,7 @@ die_if_kernel(char * str, struct pt_regs *regs, long err, unsigned long *r9_15) local_irq_enable(); while (1); } - do_exit(SIGSEGV); + make_task_dead(SIGSEGV); }
#ifndef CONFIG_MATHEMU @@ -577,7 +577,7 @@ do_entUna(void * va, unsigned long opcode, unsigned long reg,
printk("Bad unaligned kernel access at %016lx: %p %lx %lu\n", pc, va, opcode, reg); - do_exit(SIGSEGV); + make_task_dead(SIGSEGV);
got_exception: /* Ok, we caught the exception, but we don't want it. Is there @@ -632,7 +632,7 @@ do_entUna(void * va, unsigned long opcode, unsigned long reg, local_irq_enable(); while (1); } - do_exit(SIGSEGV); + make_task_dead(SIGSEGV); }
/* diff --git a/arch/alpha/mm/fault.c b/arch/alpha/mm/fault.c index eee5102c3d889..e9193d52222ea 100644 --- a/arch/alpha/mm/fault.c +++ b/arch/alpha/mm/fault.c @@ -204,7 +204,7 @@ do_page_fault(unsigned long address, unsigned long mmcsr, printk(KERN_ALERT "Unable to handle kernel paging request at " "virtual address %016lx\n", address); die_if_kernel("Oops", regs, cause, (unsigned long*)regs - 16); - do_exit(SIGKILL); + make_task_dead(SIGKILL);
/* We ran out of memory, or some other thing happened to us that made us unable to handle the page fault gracefully. */ diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c index 54abd8720ddef..91e757bb054e6 100644 --- a/arch/arm/kernel/traps.c +++ b/arch/arm/kernel/traps.c @@ -334,7 +334,7 @@ static void oops_end(unsigned long flags, struct pt_regs *regs, int signr) if (panic_on_oops) panic("Fatal exception"); if (signr) - do_exit(signr); + make_task_dead(signr); }
/* diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c index efa4020250315..af5177801fb10 100644 --- a/arch/arm/mm/fault.c +++ b/arch/arm/mm/fault.c @@ -125,7 +125,7 @@ __do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr, show_pte(KERN_ALERT, mm, addr); die("Oops", regs, fsr); bust_spinlocks(0); - do_exit(SIGKILL); + make_task_dead(SIGKILL); }
/* diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index f859cc870d5b3..21e69a991bc83 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -235,7 +235,7 @@ void die(const char *str, struct pt_regs *regs, int err) raw_spin_unlock_irqrestore(&die_lock, flags);
if (ret != NOTIFY_STOP) - do_exit(SIGSEGV); + make_task_dead(SIGSEGV); }
static void arm64_show_signal(int signo, const char *str) diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index d09b21faa0b23..97a93ee756a2e 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -302,7 +302,7 @@ static void die_kernel_fault(const char *msg, unsigned long addr, show_pte(addr); die("Oops", regs, esr); bust_spinlocks(0); - do_exit(SIGKILL); + make_task_dead(SIGKILL); }
#ifdef CONFIG_KASAN_HW_TAGS diff --git a/arch/csky/abiv1/alignment.c b/arch/csky/abiv1/alignment.c index cb2a0d94a144d..5e2fb45d605cf 100644 --- a/arch/csky/abiv1/alignment.c +++ b/arch/csky/abiv1/alignment.c @@ -294,7 +294,7 @@ void csky_alignment(struct pt_regs *regs) __func__, opcode, rz, rx, imm, addr); show_regs(regs); bust_spinlocks(0); - do_exit(SIGKILL); + make_dead_task(SIGKILL); }
force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *)addr); diff --git a/arch/csky/kernel/traps.c b/arch/csky/kernel/traps.c index 2020af88b6361..b445c5aee220b 100644 --- a/arch/csky/kernel/traps.c +++ b/arch/csky/kernel/traps.c @@ -109,7 +109,7 @@ void die(struct pt_regs *regs, const char *str) if (panic_on_oops) panic("Fatal exception"); if (ret != NOTIFY_STOP) - do_exit(SIGSEGV); + make_dead_task(SIGSEGV); }
void do_trap(struct pt_regs *regs, int signo, int code, unsigned long addr) diff --git a/arch/csky/mm/fault.c b/arch/csky/mm/fault.c index 466ad949818a6..7215a46b6b8eb 100644 --- a/arch/csky/mm/fault.c +++ b/arch/csky/mm/fault.c @@ -67,7 +67,7 @@ static inline void no_context(struct pt_regs *regs, unsigned long addr) pr_alert("Unable to handle kernel paging request at virtual " "addr 0x%08lx, pc: 0x%08lx\n", addr, regs->pc); die(regs, "Oops"); - do_exit(SIGKILL); + make_task_dead(SIGKILL); }
static inline void mm_fault_error(struct pt_regs *regs, unsigned long addr, vm_fault_t fault) diff --git a/arch/h8300/kernel/traps.c b/arch/h8300/kernel/traps.c index bdbe988d8dbcf..3d4e0bde37ae7 100644 --- a/arch/h8300/kernel/traps.c +++ b/arch/h8300/kernel/traps.c @@ -106,7 +106,7 @@ void die(const char *str, struct pt_regs *fp, unsigned long err) dump(fp);
spin_unlock_irq(&die_lock); - do_exit(SIGSEGV); + make_dead_task(SIGSEGV); }
static int kstack_depth_to_print = 24; diff --git a/arch/h8300/mm/fault.c b/arch/h8300/mm/fault.c index d4bc9c16f2df9..0223528565dd3 100644 --- a/arch/h8300/mm/fault.c +++ b/arch/h8300/mm/fault.c @@ -51,7 +51,7 @@ asmlinkage int do_page_fault(struct pt_regs *regs, unsigned long address, printk(" at virtual address %08lx\n", address); if (!user_mode(regs)) die("Oops", regs, error_code); - do_exit(SIGKILL); + make_dead_task(SIGKILL);
return 1; } diff --git a/arch/hexagon/kernel/traps.c b/arch/hexagon/kernel/traps.c index edfc35dafeb19..6dd6cf0ab711f 100644 --- a/arch/hexagon/kernel/traps.c +++ b/arch/hexagon/kernel/traps.c @@ -214,7 +214,7 @@ int die(const char *str, struct pt_regs *regs, long err) panic("Fatal exception");
oops_exit(); - do_exit(err); + make_dead_task(err); return 0; }
diff --git a/arch/ia64/kernel/mca_drv.c b/arch/ia64/kernel/mca_drv.c index 5bfc79be4cefe..23c203639a968 100644 --- a/arch/ia64/kernel/mca_drv.c +++ b/arch/ia64/kernel/mca_drv.c @@ -176,7 +176,7 @@ mca_handler_bh(unsigned long paddr, void *iip, unsigned long ipsr) spin_unlock(&mca_bh_lock);
/* This process is about to be killed itself */ - do_exit(SIGKILL); + make_task_dead(SIGKILL); }
/** diff --git a/arch/ia64/kernel/traps.c b/arch/ia64/kernel/traps.c index e13cb905930fb..753642366e12e 100644 --- a/arch/ia64/kernel/traps.c +++ b/arch/ia64/kernel/traps.c @@ -85,7 +85,7 @@ die (const char *str, struct pt_regs *regs, long err) if (panic_on_oops) panic("Fatal exception");
- do_exit(SIGSEGV); + make_task_dead(SIGSEGV); return 0; }
diff --git a/arch/ia64/mm/fault.c b/arch/ia64/mm/fault.c index 02de2e70c5874..4796cccbf74f3 100644 --- a/arch/ia64/mm/fault.c +++ b/arch/ia64/mm/fault.c @@ -259,7 +259,7 @@ ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *re regs = NULL; bust_spinlocks(0); if (regs) - do_exit(SIGKILL); + make_task_dead(SIGKILL); return;
out_of_memory: diff --git a/arch/m68k/kernel/traps.c b/arch/m68k/kernel/traps.c index 34d6458340b0f..59fc63feb0dcc 100644 --- a/arch/m68k/kernel/traps.c +++ b/arch/m68k/kernel/traps.c @@ -1131,7 +1131,7 @@ void die_if_kernel (char *str, struct pt_regs *fp, int nr) pr_crit("%s: %08x\n", str, nr); show_registers(fp); add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE); - do_exit(SIGSEGV); + make_task_dead(SIGSEGV); }
asmlinkage void set_esp0(unsigned long ssp) diff --git a/arch/m68k/mm/fault.c b/arch/m68k/mm/fault.c index ef46e77e97a5b..fcb3a0d8421c5 100644 --- a/arch/m68k/mm/fault.c +++ b/arch/m68k/mm/fault.c @@ -48,7 +48,7 @@ int send_fault_sig(struct pt_regs *regs) pr_alert("Unable to handle kernel access"); pr_cont(" at virtual address %p\n", addr); die_if_kernel("Oops", regs, 0 /*error_code*/); - do_exit(SIGKILL); + make_task_dead(SIGKILL); }
return 1; diff --git a/arch/microblaze/kernel/exceptions.c b/arch/microblaze/kernel/exceptions.c index 908788497b287..fd153d5fab982 100644 --- a/arch/microblaze/kernel/exceptions.c +++ b/arch/microblaze/kernel/exceptions.c @@ -44,10 +44,10 @@ void die(const char *str, struct pt_regs *fp, long err) pr_warn("Oops: %s, sig: %ld\n", str, err); show_regs(fp); spin_unlock_irq(&die_lock); - /* do_exit() should take care of panic'ing from an interrupt + /* make_task_dead() should take care of panic'ing from an interrupt * context so we don't handle it here */ - do_exit(err); + make_task_dead(err); }
/* for user application debugging */ diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c index edd93430b954a..afb2c955d99ef 100644 --- a/arch/mips/kernel/traps.c +++ b/arch/mips/kernel/traps.c @@ -416,7 +416,7 @@ void __noreturn die(const char *str, struct pt_regs *regs) if (regs && kexec_should_crash(current)) crash_kexec(regs);
- do_exit(sig); + make_task_dead(sig); }
extern struct exception_table_entry __start___dbe_table[]; diff --git a/arch/nds32/kernel/fpu.c b/arch/nds32/kernel/fpu.c index 9edd7ed7d7bf8..701c09a668de4 100644 --- a/arch/nds32/kernel/fpu.c +++ b/arch/nds32/kernel/fpu.c @@ -223,7 +223,7 @@ inline void handle_fpu_exception(struct pt_regs *regs) } } else if (fpcsr & FPCSR_mskRIT) { if (!user_mode(regs)) - do_exit(SIGILL); + make_task_dead(SIGILL); si_signo = SIGILL; }
diff --git a/arch/nds32/kernel/traps.c b/arch/nds32/kernel/traps.c index f06421c645aff..b90030e8e546f 100644 --- a/arch/nds32/kernel/traps.c +++ b/arch/nds32/kernel/traps.c @@ -141,7 +141,7 @@ void die(const char *str, struct pt_regs *regs, int err)
bust_spinlocks(0); spin_unlock_irq(&die_lock); - do_exit(SIGSEGV); + make_task_dead(SIGSEGV); }
EXPORT_SYMBOL(die); @@ -240,7 +240,7 @@ void unhandled_interruption(struct pt_regs *regs) pr_emerg("unhandled_interruption\n"); show_regs(regs); if (!user_mode(regs)) - do_exit(SIGKILL); + make_task_dead(SIGKILL); force_sig(SIGKILL); }
@@ -251,7 +251,7 @@ void unhandled_exceptions(unsigned long entry, unsigned long addr, addr, type); show_regs(regs); if (!user_mode(regs)) - do_exit(SIGKILL); + make_task_dead(SIGKILL); force_sig(SIGKILL); }
@@ -278,7 +278,7 @@ void do_revinsn(struct pt_regs *regs) pr_emerg("Reserved Instruction\n"); show_regs(regs); if (!user_mode(regs)) - do_exit(SIGILL); + make_task_dead(SIGILL); force_sig(SIGILL); }
diff --git a/arch/nios2/kernel/traps.c b/arch/nios2/kernel/traps.c index 596986a74a26d..85ac49d64cf73 100644 --- a/arch/nios2/kernel/traps.c +++ b/arch/nios2/kernel/traps.c @@ -37,10 +37,10 @@ void die(const char *str, struct pt_regs *regs, long err) show_regs(regs); spin_unlock_irq(&die_lock); /* - * do_exit() should take care of panic'ing from an interrupt + * make_task_dead() should take care of panic'ing from an interrupt * context so we don't handle it here */ - do_exit(err); + make_task_dead(err); }
void _exception(int signo, struct pt_regs *regs, int code, unsigned long addr) diff --git a/arch/openrisc/kernel/traps.c b/arch/openrisc/kernel/traps.c index aa1e709405acd..9df1d85bfe1d1 100644 --- a/arch/openrisc/kernel/traps.c +++ b/arch/openrisc/kernel/traps.c @@ -212,7 +212,7 @@ void die(const char *str, struct pt_regs *regs, long err) __asm__ __volatile__("l.nop 1"); do {} while (1); #endif - do_exit(SIGSEGV); + make_task_dead(SIGSEGV); }
/* This is normally the 'Oops' routine */ diff --git a/arch/parisc/kernel/traps.c b/arch/parisc/kernel/traps.c index 6fe5a3e98edc2..70ace36879507 100644 --- a/arch/parisc/kernel/traps.c +++ b/arch/parisc/kernel/traps.c @@ -268,7 +268,7 @@ void die_if_kernel(char *str, struct pt_regs *regs, long err) panic("Fatal exception");
oops_exit(); - do_exit(SIGSEGV); + make_task_dead(SIGSEGV); }
/* gdb uses break 4,8 */ diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c index 11741703d26e0..a08bb7cefdc54 100644 --- a/arch/powerpc/kernel/traps.c +++ b/arch/powerpc/kernel/traps.c @@ -245,7 +245,7 @@ static void oops_end(unsigned long flags, struct pt_regs *regs,
if (panic_on_oops) panic("Fatal exception"); - do_exit(signr); + make_task_dead(signr); } NOKPROBE_SYMBOL(oops_end);
@@ -792,9 +792,9 @@ int machine_check_generic(struct pt_regs *regs) void die_mce(const char *str, struct pt_regs *regs, long err) { /* - * The machine check wants to kill the interrupted context, but - * do_exit() checks for in_interrupt() and panics in that case, so - * exit the irq/nmi before calling die. + * The machine check wants to kill the interrupted context, + * but make_task_dead() checks for in_interrupt() and panics + * in that case, so exit the irq/nmi before calling die. */ if (in_nmi()) nmi_exit(); diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c index 4102c97309cc2..6084bd93d2f58 100644 --- a/arch/riscv/kernel/traps.c +++ b/arch/riscv/kernel/traps.c @@ -59,7 +59,7 @@ void die(struct pt_regs *regs, const char *str) if (panic_on_oops) panic("Fatal exception"); if (ret != NOTIFY_STOP) - do_exit(SIGSEGV); + make_task_dead(SIGSEGV); }
void do_trap(struct pt_regs *regs, int signo, int code, unsigned long addr) diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c index 7cfaf366463fb..676a3f28811fa 100644 --- a/arch/riscv/mm/fault.c +++ b/arch/riscv/mm/fault.c @@ -31,7 +31,7 @@ static void die_kernel_fault(const char *msg, unsigned long addr,
bust_spinlocks(0); die(regs, "Oops"); - do_exit(SIGKILL); + make_task_dead(SIGKILL); }
static inline void no_context(struct pt_regs *regs, unsigned long addr) diff --git a/arch/s390/kernel/dumpstack.c b/arch/s390/kernel/dumpstack.c index db1bc00229caf..272ef8597e208 100644 --- a/arch/s390/kernel/dumpstack.c +++ b/arch/s390/kernel/dumpstack.c @@ -224,5 +224,5 @@ void die(struct pt_regs *regs, const char *str) if (panic_on_oops) panic("Fatal exception: panic_on_oops"); oops_exit(); - do_exit(SIGSEGV); + make_task_dead(SIGSEGV); } diff --git a/arch/s390/kernel/nmi.c b/arch/s390/kernel/nmi.c index 383b4799b6dd3..d4f071e73a0a6 100644 --- a/arch/s390/kernel/nmi.c +++ b/arch/s390/kernel/nmi.c @@ -175,7 +175,7 @@ void __s390_handle_mcck(void) "malfunction (code 0x%016lx).\n", mcck.mcck_code); printk(KERN_EMERG "mcck: task: %s, pid: %d.\n", current->comm, current->pid); - do_exit(SIGSEGV); + make_task_dead(SIGSEGV); } }
diff --git a/arch/sh/kernel/traps.c b/arch/sh/kernel/traps.c index e76b221570999..361b764700b74 100644 --- a/arch/sh/kernel/traps.c +++ b/arch/sh/kernel/traps.c @@ -57,7 +57,7 @@ void die(const char *str, struct pt_regs *regs, long err) if (panic_on_oops) panic("Fatal exception");
- do_exit(SIGSEGV); + make_task_dead(SIGSEGV); }
void die_if_kernel(const char *str, struct pt_regs *regs, long err) diff --git a/arch/sparc/kernel/traps_32.c b/arch/sparc/kernel/traps_32.c index 5630e5a395e0d..179aabfa712ea 100644 --- a/arch/sparc/kernel/traps_32.c +++ b/arch/sparc/kernel/traps_32.c @@ -86,9 +86,7 @@ void __noreturn die_if_kernel(char *str, struct pt_regs *regs) } printk("Instruction DUMP:"); instruction_dump ((unsigned long *) regs->pc); - if(regs->psr & PSR_PS) - do_exit(SIGKILL); - do_exit(SIGSEGV); + make_task_dead((regs->psr & PSR_PS) ? SIGKILL : SIGSEGV); }
void do_hw_interrupt(struct pt_regs *regs, unsigned long type) diff --git a/arch/sparc/kernel/traps_64.c b/arch/sparc/kernel/traps_64.c index 6863025ed56d2..21077821f4272 100644 --- a/arch/sparc/kernel/traps_64.c +++ b/arch/sparc/kernel/traps_64.c @@ -2559,9 +2559,7 @@ void __noreturn die_if_kernel(char *str, struct pt_regs *regs) } if (panic_on_oops) panic("Fatal exception"); - if (regs->tstate & TSTATE_PRIV) - do_exit(SIGKILL); - do_exit(SIGSEGV); + make_task_dead((regs->tstate & TSTATE_PRIV)? SIGKILL : SIGSEGV); } EXPORT_SYMBOL(die_if_kernel);
diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index 6b44263d7efbc..e309e71560389 100644 --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -1239,14 +1239,14 @@ SYM_CODE_START(asm_exc_nmi) SYM_CODE_END(asm_exc_nmi)
.pushsection .text, "ax" -SYM_CODE_START(rewind_stack_do_exit) +SYM_CODE_START(rewind_stack_and_make_dead) /* Prevent any naive code from trying to unwind to our caller. */ xorl %ebp, %ebp
movl PER_CPU_VAR(cpu_current_top_of_stack), %esi leal -TOP_OF_KERNEL_STACK_PADDING-PTREGS_SIZE(%esi), %esp
- call do_exit + call make_task_dead 1: jmp 1b -SYM_CODE_END(rewind_stack_do_exit) +SYM_CODE_END(rewind_stack_and_make_dead) .popsection diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index a3af2a9159b1b..9f1333a9ee41d 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -1487,7 +1487,7 @@ SYM_CODE_END(ignore_sysret) #endif
.pushsection .text, "ax" -SYM_CODE_START(rewind_stack_do_exit) +SYM_CODE_START(rewind_stack_and_make_dead) UNWIND_HINT_FUNC /* Prevent any naive code from trying to unwind to our caller. */ xorl %ebp, %ebp @@ -1496,6 +1496,6 @@ SYM_CODE_START(rewind_stack_do_exit) leaq -PTREGS_SIZE(%rax), %rsp UNWIND_HINT_REGS
- call do_exit -SYM_CODE_END(rewind_stack_do_exit) + call make_task_dead +SYM_CODE_END(rewind_stack_and_make_dead) .popsection diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c index ea4fe192189d5..53de044e56540 100644 --- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -351,7 +351,7 @@ unsigned long oops_begin(void) } NOKPROBE_SYMBOL(oops_begin);
-void __noreturn rewind_stack_do_exit(int signr); +void __noreturn rewind_stack_and_make_dead(int signr);
void oops_end(unsigned long flags, struct pt_regs *regs, int signr) { @@ -386,7 +386,7 @@ void oops_end(unsigned long flags, struct pt_regs *regs, int signr) * reuse the task stack and that existing poisons are invalid. */ kasan_unpoison_task_stack(current); - rewind_stack_do_exit(signr); + rewind_stack_and_make_dead(signr); } NOKPROBE_SYMBOL(oops_end);
diff --git a/arch/xtensa/kernel/traps.c b/arch/xtensa/kernel/traps.c index 874b6efc6fb31..904086ad56827 100644 --- a/arch/xtensa/kernel/traps.c +++ b/arch/xtensa/kernel/traps.c @@ -552,5 +552,5 @@ void die(const char * str, struct pt_regs * regs, long err) if (panic_on_oops) panic("Fatal exception");
- do_exit(err); + make_task_dead(err); } diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h index caae8e045160d..d351f1b362ef9 100644 --- a/include/linux/sched/task.h +++ b/include/linux/sched/task.h @@ -59,6 +59,7 @@ extern void sched_post_fork(struct task_struct *p); extern void sched_dead(struct task_struct *p);
void __noreturn do_task_dead(void); +void __noreturn make_task_dead(int signr);
extern void proc_caches_init(void);
diff --git a/kernel/exit.c b/kernel/exit.c index aefe7445508db..5d1a507fd4bae 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -877,6 +877,15 @@ void __noreturn do_exit(long code) } EXPORT_SYMBOL_GPL(do_exit);
+void __noreturn make_task_dead(int signr) +{ + /* + * Take the task off the cpu after something catastrophic has + * happened. + */ + do_exit(signr); +} + void complete_and_exit(struct completion *comp, long code) { if (comp) diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 308c8806ad94e..82ade76dcef2f 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -169,6 +169,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func, "panic", "do_exit", "do_task_dead", + "make_task_dead", "__module_put_and_exit", "complete_and_exit", "__reiserfs_panic", @@ -176,7 +177,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func, "fortify_panic", "usercopy_abort", "machine_real_restart", - "rewind_stack_do_exit", + "rewind_stack_and_make_dead" "kunit_try_catch_throw", "xen_start_kernel", "cpu_bringup_and_idle",
From: "Eric W. Biederman" ebiederm@xmission.com
commit 1fb466dff904e4a72282af336f2c355f011eec61 upstream.
Recently the kbuild robot reported two new errors:
lib/kunit/kunit-example-test.o: warning: objtool: .text.unlikely: unexpected end of section arch/x86/kernel/dumpstack.o: warning: objtool: oops_end() falls through to next function show_opcodes()
I don't know why they did not occur in my test setup but after digging it I realized I had accidentally dropped a comma in tools/objtool/check.c when I renamed rewind_stack_do_exit to rewind_stack_and_make_dead.
Add that comma back to fix objtool errors.
Link: https://lkml.kernel.org/r/202112140949.Uq5sFKR1-lkp@intel.com Fixes: 0e25498f8cd4 ("exit: Add and use make_task_dead.") Reported-by: kernel test robot lkp@intel.com Signed-off-by: "Eric W. Biederman" ebiederm@xmission.com Signed-off-by: Eric Biggers ebiggers@google.com --- tools/objtool/check.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 82ade76dcef2f..758c0ba8de350 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -177,7 +177,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func, "fortify_panic", "usercopy_abort", "machine_real_restart", - "rewind_stack_and_make_dead" + "rewind_stack_and_make_dead", "kunit_try_catch_throw", "xen_start_kernel", "cpu_bringup_and_idle",
From: Nathan Chancellor nathan@kernel.org
commit 4f0712ccec09c071e221242a2db9a6779a55a949 upstream.
When building ARCH=hexagon defconfig:
arch/hexagon/kernel/traps.c:217:2: error: implicit declaration of function 'make_dead_task' [-Werror,-Wimplicit-function-declaration] make_dead_task(err); ^
The function's name is make_task_dead(), change it so there is no more build error.
Fixes: 0e25498f8cd4 ("exit: Add and use make_task_dead.") Signed-off-by: Nathan Chancellor nathan@kernel.org Link: https://lkml.kernel.org/r/20211227184851.2297759-2-nathan@kernel.org Signed-off-by: Eric W. Biederman ebiederm@xmission.com Signed-off-by: Eric Biggers ebiggers@google.com --- arch/hexagon/kernel/traps.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/hexagon/kernel/traps.c b/arch/hexagon/kernel/traps.c index 6dd6cf0ab711f..1240f038cce02 100644 --- a/arch/hexagon/kernel/traps.c +++ b/arch/hexagon/kernel/traps.c @@ -214,7 +214,7 @@ int die(const char *str, struct pt_regs *regs, long err) panic("Fatal exception");
oops_exit(); - make_dead_task(err); + make_task_dead(err); return 0; }
From: Nathan Chancellor nathan@kernel.org
commit ab4ababdf77ccc56c7301c751dff49c79709c51c upstream.
When building ARCH=h8300 defconfig:
arch/h8300/kernel/traps.c: In function 'die': arch/h8300/kernel/traps.c:109:2: error: implicit declaration of function 'make_dead_task' [-Werror=implicit-function-declaration] 109 | make_dead_task(SIGSEGV); | ^~~~~~~~~~~~~~
arch/h8300/mm/fault.c: In function 'do_page_fault': arch/h8300/mm/fault.c:54:2: error: implicit declaration of function 'make_dead_task' [-Werror=implicit-function-declaration] 54 | make_dead_task(SIGKILL); | ^~~~~~~~~~~~~~
The function's name is make_task_dead(), change it so there is no more build error.
Additionally, include linux/sched/task.h in arch/h8300/kernel/traps.c to avoid the same error because do_exit()'s declaration is in kernel.h but make_task_dead()'s is in task.h, which is not included in traps.c.
Fixes: 0e25498f8cd4 ("exit: Add and use make_task_dead.") Signed-off-by: Nathan Chancellor nathan@kernel.org Link: https://lkml.kernel.org/r/20211227184851.2297759-3-nathan@kernel.org Signed-off-by: Eric W. Biederman ebiederm@xmission.com Signed-off-by: Eric Biggers ebiggers@google.com --- arch/h8300/kernel/traps.c | 3 ++- arch/h8300/mm/fault.c | 2 +- 2 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/h8300/kernel/traps.c b/arch/h8300/kernel/traps.c index 3d4e0bde37ae7..a92c39e03802e 100644 --- a/arch/h8300/kernel/traps.c +++ b/arch/h8300/kernel/traps.c @@ -17,6 +17,7 @@ #include <linux/types.h> #include <linux/sched.h> #include <linux/sched/debug.h> +#include <linux/sched/task.h> #include <linux/mm_types.h> #include <linux/kernel.h> #include <linux/errno.h> @@ -106,7 +107,7 @@ void die(const char *str, struct pt_regs *fp, unsigned long err) dump(fp);
spin_unlock_irq(&die_lock); - make_dead_task(SIGSEGV); + make_task_dead(SIGSEGV); }
static int kstack_depth_to_print = 24; diff --git a/arch/h8300/mm/fault.c b/arch/h8300/mm/fault.c index 0223528565dd3..b465441f490df 100644 --- a/arch/h8300/mm/fault.c +++ b/arch/h8300/mm/fault.c @@ -51,7 +51,7 @@ asmlinkage int do_page_fault(struct pt_regs *regs, unsigned long address, printk(" at virtual address %08lx\n", address); if (!user_mode(regs)) die("Oops", regs, error_code); - make_dead_task(SIGKILL); + make_task_dead(SIGKILL);
return 1; }
From: Nathan Chancellor nathan@kernel.org
commit 751971af2e3615dc5bd12674080bc795505fefeb upstream.
When building ARCH=csky defconfig:
arch/csky/kernel/traps.c: In function 'die': arch/csky/kernel/traps.c:112:17: error: implicit declaration of function 'make_dead_task' [-Werror=implicit-function-declaration] 112 | make_dead_task(SIGSEGV); | ^~~~~~~~~~~~~~
The function's name is make_task_dead(), change it so there is no more build error.
Fixes: 0e25498f8cd4 ("exit: Add and use make_task_dead.") Signed-off-by: Nathan Chancellor nathan@kernel.org Reviewed-by: Guo Ren guoren@kernel.org Link: https://lkml.kernel.org/r/20211227184851.2297759-4-nathan@kernel.org Signed-off-by: Eric W. Biederman ebiederm@xmission.com Signed-off-by: Eric Biggers ebiggers@google.com --- arch/csky/abiv1/alignment.c | 2 +- arch/csky/kernel/traps.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/csky/abiv1/alignment.c b/arch/csky/abiv1/alignment.c index 5e2fb45d605cf..2df115d0e2105 100644 --- a/arch/csky/abiv1/alignment.c +++ b/arch/csky/abiv1/alignment.c @@ -294,7 +294,7 @@ void csky_alignment(struct pt_regs *regs) __func__, opcode, rz, rx, imm, addr); show_regs(regs); bust_spinlocks(0); - make_dead_task(SIGKILL); + make_task_dead(SIGKILL); }
force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *)addr); diff --git a/arch/csky/kernel/traps.c b/arch/csky/kernel/traps.c index b445c5aee220b..6e426fba01193 100644 --- a/arch/csky/kernel/traps.c +++ b/arch/csky/kernel/traps.c @@ -109,7 +109,7 @@ void die(struct pt_regs *regs, const char *str) if (panic_on_oops) panic("Fatal exception"); if (ret != NOTIFY_STOP) - make_dead_task(SIGSEGV); + make_task_dead(SIGSEGV); }
void do_trap(struct pt_regs *regs, int signo, int code, unsigned long addr)
From: Randy Dunlap rdunlap@infradead.org
commit dbecf9b8b8ce580f4e11afed9d61e8aa294cddd2 upstream.
In linux-next, IA64_MCA_RECOVERY uses the (new) function make_task_dead(), which is not exported for use by modules. Instead of exporting it for one user, convert IA64_MCA_RECOVERY to be a bool Kconfig symbol.
In a config file from "kernel test robot lkp@intel.com" for a different problem, this linker error was exposed when CONFIG_IA64_MCA_RECOVERY=m.
Fixes this build error:
ERROR: modpost: "make_task_dead" [arch/ia64/kernel/mca_recovery.ko] undefined!
Link: https://lkml.kernel.org/r/20220124213129.29306-1-rdunlap@infradead.org Fixes: 0e25498f8cd4 ("exit: Add and use make_task_dead.") Signed-off-by: Randy Dunlap rdunlap@infradead.org Suggested-by: Christoph Hellwig hch@infradead.org Reviewed-by: Christoph Hellwig hch@lst.de Reviewed-by: "Eric W. Biederman" ebiederm@xmission.com Cc: Tony Luck tony.luck@intel.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Eric Biggers ebiggers@google.com --- arch/ia64/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig index 1e33666fa679b..b1f2b6ac9b1d5 100644 --- a/arch/ia64/Kconfig +++ b/arch/ia64/Kconfig @@ -323,7 +323,7 @@ config ARCH_PROC_KCORE_TEXT depends on PROC_KCORE
config IA64_MCA_RECOVERY - tristate "MCA recovery from errors other than TLB." + bool "MCA recovery from errors other than TLB."
config IA64_PALINFO tristate "/proc/pal support"
From: Kees Cook keescook@chromium.org
commit 9360d035a579d95d1e76c471061b9065b18a0eb1 upstream.
In preparation for adding more sysctls directly in kernel/panic.c, split CONFIG_SMP from the logic that adds sysctls.
Cc: Petr Mladek pmladek@suse.com Cc: Andrew Morton akpm@linux-foundation.org Cc: tangmeng tangmeng@uniontech.com Cc: "Guilherme G. Piccoli" gpiccoli@igalia.com Cc: Tiezhu Yang yangtiezhu@loongson.cn Cc: Sebastian Andrzej Siewior bigeasy@linutronix.de Reviewed-by: Luis Chamberlain mcgrof@kernel.org Signed-off-by: Kees Cook keescook@chromium.org Link: https://lore.kernel.org/r/20221117234328.594699-1-keescook@chromium.org Signed-off-by: Eric Biggers ebiggers@google.com --- kernel/panic.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/kernel/panic.c b/kernel/panic.c index 5ed1ad06f9a34..0b560312878c5 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -73,8 +73,9 @@ ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
EXPORT_SYMBOL(panic_notifier_list);
-#if defined(CONFIG_SMP) && defined(CONFIG_SYSCTL) +#ifdef CONFIG_SYSCTL static struct ctl_table kern_panic_table[] = { +#ifdef CONFIG_SMP { .procname = "oops_all_cpu_backtrace", .data = &sysctl_oops_all_cpu_backtrace, @@ -84,6 +85,7 @@ static struct ctl_table kern_panic_table[] = { .extra1 = SYSCTL_ZERO, .extra2 = SYSCTL_ONE, }, +#endif { } };
From: Jann Horn jannh@google.com
commit d4ccd54d28d3c8598e2354acc13e28c060961dbb upstream.
Many Linux systems are configured to not panic on oops; but allowing an attacker to oops the system **really** often can make even bugs that look completely unexploitable exploitable (like NULL dereferences and such) if each crash elevates a refcount by one or a lock is taken in read mode, and this causes a counter to eventually overflow.
The most interesting counters for this are 32 bits wide (like open-coded refcounts that don't use refcount_t). (The ldsem reader count on 32-bit platforms is just 16 bits, but probably nobody cares about 32-bit platforms that much nowadays.)
So let's panic the system if the kernel is constantly oopsing.
The speed of oopsing 2^32 times probably depends on several factors, like how long the stack trace is and which unwinder you're using; an empirically important one is whether your console is showing a graphical environment or a text console that oopses will be printed to. In a quick single-threaded benchmark, it looks like oopsing in a vfork() child with a very short stack trace only takes ~510 microseconds per run when a graphical console is active; but switching to a text console that oopses are printed to slows it down around 87x, to ~45 milliseconds per run. (Adding more threads makes this faster, but the actual oops printing happens under &die_lock on x86, so you can maybe speed this up by a factor of around 2 and then any further improvement gets eaten up by lock contention.)
It looks like it would take around 8-12 days to overflow a 32-bit counter with repeated oopsing on a multi-core X86 system running a graphical environment; both me (in an X86 VM) and Seth (with a distro kernel on normal hardware in a standard configuration) got numbers in that ballpark.
12 days aren't *that* short on a desktop system, and you'd likely need much longer on a typical server system (assuming that people don't run graphical desktop environments on their servers), and this is a *very* noisy and violent approach to exploiting the kernel; and it also seems to take orders of magnitude longer on some machines, probably because stuff like EFI pstore will slow it down a ton if that's active.
Signed-off-by: Jann Horn jannh@google.com Link: https://lore.kernel.org/r/20221107201317.324457-1-jannh@google.com Reviewed-by: Luis Chamberlain mcgrof@kernel.org Signed-off-by: Kees Cook keescook@chromium.org Link: https://lore.kernel.org/r/20221117234328.594699-2-keescook@chromium.org Signed-off-by: Eric Biggers ebiggers@google.com --- Documentation/admin-guide/sysctl/kernel.rst | 8 ++++ kernel/exit.c | 43 +++++++++++++++++++++ 2 files changed, 51 insertions(+)
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index 609b891754081..b6e68d6f297e5 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -671,6 +671,14 @@ This is the default behavior. an oops event is detected.
+oops_limit +========== + +Number of kernel oopses after which the kernel should panic when +``panic_on_oops`` is not set. Setting this to 0 or 1 has the same effect +as setting ``panic_on_oops=1``. + + osrelease, ostype & version ===========================
diff --git a/kernel/exit.c b/kernel/exit.c index 5d1a507fd4bae..172d7f835f801 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -69,6 +69,33 @@ #include <asm/unistd.h> #include <asm/mmu_context.h>
+/* + * The default value should be high enough to not crash a system that randomly + * crashes its kernel from time to time, but low enough to at least not permit + * overflowing 32-bit refcounts or the ldsem writer count. + */ +static unsigned int oops_limit = 10000; + +#ifdef CONFIG_SYSCTL +static struct ctl_table kern_exit_table[] = { + { + .procname = "oops_limit", + .data = &oops_limit, + .maxlen = sizeof(oops_limit), + .mode = 0644, + .proc_handler = proc_douintvec, + }, + { } +}; + +static __init int kernel_exit_sysctls_init(void) +{ + register_sysctl_init("kernel", kern_exit_table); + return 0; +} +late_initcall(kernel_exit_sysctls_init); +#endif + static void __unhash_process(struct task_struct *p, bool group_dead) { nr_threads--; @@ -879,10 +906,26 @@ EXPORT_SYMBOL_GPL(do_exit);
void __noreturn make_task_dead(int signr) { + static atomic_t oops_count = ATOMIC_INIT(0); + /* * Take the task off the cpu after something catastrophic has * happened. */ + + /* + * Every time the system oopses, if the oops happens while a reference + * to an object was held, the reference leaks. + * If the oops doesn't also leak memory, repeated oopsing can cause + * reference counters to wrap around (if they're not using refcount_t). + * This means that repeated oopsing can make unexploitable-looking bugs + * exploitable through repeated oopsing. + * To make sure this can't happen, place an upper bound on how often the + * kernel may oops without panic(). + */ + if (atomic_inc_return(&oops_count) >= READ_ONCE(oops_limit)) + panic("Oopsed too often (kernel.oops_limit is %d)", oops_limit); + do_exit(signr); }
On 25/01/23 12:21 am, Eric Biggers wrote:
From: Jann Horn jannh@google.com
commit d4ccd54d28d3c8598e2354acc13e28c060961dbb upstream.
Many Linux systems are configured to not panic on oops; but allowing an attacker to oops the system **really** often can make even bugs that look completely unexploitable exploitable (like NULL dereferences and such) if each crash elevates a refcount by one or a lock is taken in read mode, and this causes a counter to eventually overflow.
The most interesting counters for this are 32 bits wide (like open-coded refcounts that don't use refcount_t). (The ldsem reader count on 32-bit platforms is just 16 bits, but probably nobody cares about 32-bit platforms that much nowadays.)
So let's panic the system if the kernel is constantly oopsing.
The speed of oopsing 2^32 times probably depends on several factors, like how long the stack trace is and which unwinder you're using; an empirically important one is whether your console is showing a graphical environment or a text console that oopses will be printed to. In a quick single-threaded benchmark, it looks like oopsing in a vfork() child with a very short stack trace only takes ~510 microseconds per run when a graphical console is active; but switching to a text console that oopses are printed to slows it down around 87x, to ~45 milliseconds per run. (Adding more threads makes this faster, but the actual oops printing happens under &die_lock on x86, so you can maybe speed this up by a factor of around 2 and then any further improvement gets eaten up by lock contention.)
It looks like it would take around 8-12 days to overflow a 32-bit counter with repeated oopsing on a multi-core X86 system running a graphical environment; both me (in an X86 VM) and Seth (with a distro kernel on normal hardware in a standard configuration) got numbers in that ballpark.
12 days aren't *that* short on a desktop system, and you'd likely need much longer on a typical server system (assuming that people don't run graphical desktop environments on their servers), and this is a *very* noisy and violent approach to exploiting the kernel; and it also seems to take orders of magnitude longer on some machines, probably because stuff like EFI pstore will slow it down a ton if that's active.
Signed-off-by: Jann Horn jannh@google.com Link: https://urldefense.com/v3/__https://lore.kernel.org/r/20221107201317.324457-... Reviewed-by: Luis Chamberlain mcgrof@kernel.org Signed-off-by: Kees Cook keescook@chromium.org Link: https://urldefense.com/v3/__https://lore.kernel.org/r/20221117234328.594699-... Signed-off-by: Eric Biggers ebiggers@google.com
Documentation/admin-guide/sysctl/kernel.rst | 8 ++++ kernel/exit.c | 43 +++++++++++++++++++++ 2 files changed, 51 insertions(+)
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index 609b891754081..b6e68d6f297e5 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -671,6 +671,14 @@ This is the default behavior. an oops event is detected. +oops_limit +==========
+Number of kernel oopses after which the kernel should panic when +``panic_on_oops`` is not set. Setting this to 0 or 1 has the same effect +as setting ``panic_on_oops=1``.
osrelease, ostype & version
diff --git a/kernel/exit.c b/kernel/exit.c index 5d1a507fd4bae..172d7f835f801 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -69,6 +69,33 @@ #include <asm/unistd.h> #include <asm/mmu_context.h> +/*
- The default value should be high enough to not crash a system that randomly
- crashes its kernel from time to time, but low enough to at least not permit
- overflowing 32-bit refcounts or the ldsem writer count.
- */
+static unsigned int oops_limit = 10000;
+#ifdef CONFIG_SYSCTL +static struct ctl_table kern_exit_table[] = {
- {
.procname = "oops_limit",.data = &oops_limit,.maxlen = sizeof(oops_limit),.mode = 0644,.proc_handler = proc_douintvec,- },
- { }
+};
+static __init int kernel_exit_sysctls_init(void) +{
- register_sysctl_init("kernel", kern_exit_table);
- return 0;
+} +late_initcall(kernel_exit_sysctls_init); +#endif
- static void __unhash_process(struct task_struct *p, bool group_dead) { nr_threads--;
@@ -879,10 +906,26 @@ EXPORT_SYMBOL_GPL(do_exit); void __noreturn make_task_dead(int signr) {
- static atomic_t oops_count = ATOMIC_INIT(0);
- /*
*/
- Take the task off the cpu after something catastrophic has
- happened.
- /*
* Every time the system oopses, if the oops happens while a reference* to an object was held, the reference leaks.* If the oops doesn't also leak memory, repeated oopsing can cause* reference counters to wrap around (if they're not using refcount_t).* This means that repeated oopsing can make unexploitable-looking bugs* exploitable through repeated oopsing.* To make sure this can't happen, place an upper bound on how often the* kernel may oops without panic().*/- if (atomic_inc_return(&oops_count) >= READ_ONCE(oops_limit))
panic("Oopsed too often (kernel.oops_limit is %d)", oops_limit);- do_exit(signr); }
Hi,
Thanks for the backports.
I have tried backporting the oops_limit patches to LTS 5.15.y and had a similar set of patches, just want to add a note here on an alternate way for backporting this patch without resolving conflicts manually:
Here is the sequence:
* Patch 12: [panic: Separate sysctl logic from CONFIG_SMP] --> Cherry-pick Commit: 05ea0424f0e2 ("exit: Move oops specific logic from do_exit into make_task_dead") upstream --> Cherry-pick Commit: de77c3a5b95c ("exit: Move force_uaccess back into do_exit") upstream * Patch 13 which is Commit: d4ccd54d28d3 ("exit: Put an upper limit on how often we can oops") upstream, will be a clean cherry-pick.
The benefit may be making future backports simpler in make_task_dead().
This was the only difference, so your backport looks good to me.
Regards, Harshit
Hi Harshit,
On Wed, Jan 25, 2023 at 07:39:10PM +0530, Harshit Mogalapalli wrote:
Thanks for the backports.
I have tried backporting the oops_limit patches to LTS 5.15.y and had a similar set of patches, just want to add a note here on an alternate way for backporting this patch without resolving conflicts manually:
Here is the sequence:
- Patch 12: [panic: Separate sysctl logic from CONFIG_SMP]
--> Cherry-pick Commit: 05ea0424f0e2 ("exit: Move oops specific logic from do_exit into make_task_dead") upstream --> Cherry-pick Commit: de77c3a5b95c ("exit: Move force_uaccess back into do_exit") upstream
- Patch 13 which is Commit: d4ccd54d28d3 ("exit: Put an upper limit on how
often we can oops") upstream, will be a clean cherry-pick.
The benefit may be making future backports simpler in make_task_dead().
This was the only difference, so your backport looks good to me.
It's certainly an option. The reason why I didn't do it that way is to reduce the impact of any potential bugs where do_exit() is still called when the new make_task_dead() function should be used instead. With my series, the effect is just that oops_limit won't take effect in such cases. If we also backported commit 05ea0424f0e2 ("exit: Move oops specific logic from do_exit into make_task_dead"), then do_exit() will lose various other things, such as panicing when called from an interrupt handler. That would increase the chance of regressions, unless we made absolutely sure that everywhere that should be using make_task_dead() is indeed using it instead of do_exit().
Commit 0e25498f8cd4 ("exit: Add and use make_task_dead."), which I backported, did the vast majority of conversions to make_task_dead().
Some architectures still have uses of do_exit() that got cleaned up later, though. It seems it was mostly unreachable code, and some cases that should have been doing something else such as BUG() or sending a signal to userspace. So, generally not super important cases.
Still, getting all that would bring in many more patches. We could do that, but since this is already a 20-patch series, I wanted to limit the scope a bit. These extra patches could always be backported later on top of this if desired.
- Eric
Hi Eric,
On 26/01/23 12:14 am, Eric Biggers wrote:
Hi Harshit,
On Wed, Jan 25, 2023 at 07:39:10PM +0530, Harshit Mogalapalli wrote:
Thanks for the backports.
I have tried backporting the oops_limit patches to LTS 5.15.y and had a similar set of patches, just want to add a note here on an alternate way for backporting this patch without resolving conflicts manually:
Here is the sequence:
- Patch 12: [panic: Separate sysctl logic from CONFIG_SMP]
--> Cherry-pick Commit: 05ea0424f0e2 ("exit: Move oops specific logic from do_exit into make_task_dead") upstream --> Cherry-pick Commit: de77c3a5b95c ("exit: Move force_uaccess back into do_exit") upstream
- Patch 13 which is Commit: d4ccd54d28d3 ("exit: Put an upper limit on how
often we can oops") upstream, will be a clean cherry-pick.
The benefit may be making future backports simpler in make_task_dead().
This was the only difference, so your backport looks good to me.
It's certainly an option. The reason why I didn't do it that way is to reduce the impact of any potential bugs where do_exit() is still called when the new make_task_dead() function should be used instead. With my series, the effect is just that oops_limit won't take effect in such cases. If we also backported commit 05ea0424f0e2 ("exit: Move oops specific logic from do_exit into make_task_dead"), then do_exit() will lose various other things, such as panicing when called from an interrupt handler. That would increase the chance of regressions, unless we made absolutely sure that everywhere that should be using make_task_dead() is indeed using it instead of do_exit().
Commit 0e25498f8cd4 ("exit: Add and use make_task_dead."), which I backported, did the vast majority of conversions to make_task_dead().
Some architectures still have uses of do_exit() that got cleaned up later, though. It seems it was mostly unreachable code, and some cases that should have been doing something else such as BUG() or sending a signal to userspace. So, generally not super important cases.
Thanks a lot for explaining!
Still, getting all that would bring in many more patches. We could do that, but since this is already a 20-patch series, I wanted to limit the scope a bit. These extra patches could always be backported later on top of this if desired.
Sure.
Regards, Harshit
- Eric
From: Kees Cook keescook@chromium.org
commit 9db89b41117024f80b38b15954017fb293133364 upstream.
Since Oops count is now tracked and is a fairly interesting signal, add the entry /sys/kernel/oops_count to expose it to userspace.
Cc: "Eric W. Biederman" ebiederm@xmission.com Cc: Jann Horn jannh@google.com Cc: Arnd Bergmann arnd@arndb.de Reviewed-by: Luis Chamberlain mcgrof@kernel.org Signed-off-by: Kees Cook keescook@chromium.org Link: https://lore.kernel.org/r/20221117234328.594699-3-keescook@chromium.org Signed-off-by: Eric Biggers ebiggers@google.com --- .../ABI/testing/sysfs-kernel-oops_count | 6 +++++ kernel/exit.c | 22 +++++++++++++++++-- 2 files changed, 26 insertions(+), 2 deletions(-) create mode 100644 Documentation/ABI/testing/sysfs-kernel-oops_count
diff --git a/Documentation/ABI/testing/sysfs-kernel-oops_count b/Documentation/ABI/testing/sysfs-kernel-oops_count new file mode 100644 index 0000000000000..156cca9dbc960 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-kernel-oops_count @@ -0,0 +1,6 @@ +What: /sys/kernel/oops_count +Date: November 2022 +KernelVersion: 6.2.0 +Contact: Linux Kernel Hardening List linux-hardening@vger.kernel.org +Description: + Shows how many times the system has Oopsed since last boot. diff --git a/kernel/exit.c b/kernel/exit.c index 172d7f835f801..f68a9c6adfc9c 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -64,6 +64,7 @@ #include <linux/rcuwait.h> #include <linux/compat.h> #include <linux/io_uring.h> +#include <linux/sysfs.h>
#include <linux/uaccess.h> #include <asm/unistd.h> @@ -96,6 +97,25 @@ static __init int kernel_exit_sysctls_init(void) late_initcall(kernel_exit_sysctls_init); #endif
+static atomic_t oops_count = ATOMIC_INIT(0); + +#ifdef CONFIG_SYSFS +static ssize_t oops_count_show(struct kobject *kobj, struct kobj_attribute *attr, + char *page) +{ + return sysfs_emit(page, "%d\n", atomic_read(&oops_count)); +} + +static struct kobj_attribute oops_count_attr = __ATTR_RO(oops_count); + +static __init int kernel_exit_sysfs_init(void) +{ + sysfs_add_file_to_group(kernel_kobj, &oops_count_attr.attr, NULL); + return 0; +} +late_initcall(kernel_exit_sysfs_init); +#endif + static void __unhash_process(struct task_struct *p, bool group_dead) { nr_threads--; @@ -906,8 +926,6 @@ EXPORT_SYMBOL_GPL(do_exit);
void __noreturn make_task_dead(int signr) { - static atomic_t oops_count = ATOMIC_INIT(0); - /* * Take the task off the cpu after something catastrophic has * happened.
From: Kees Cook keescook@chromium.org
commit de92f65719cd672f4b48397540b9f9eff67eca40 upstream.
In preparation for keeping oops_limit logic in sync with warn_limit, have oops_limit == 0 disable checking the Oops counter.
Cc: Jann Horn jannh@google.com Cc: Jonathan Corbet corbet@lwn.net Cc: Andrew Morton akpm@linux-foundation.org Cc: Baolin Wang baolin.wang@linux.alibaba.com Cc: "Jason A. Donenfeld" Jason@zx2c4.com Cc: Eric Biggers ebiggers@google.com Cc: Huang Ying ying.huang@intel.com Cc: "Eric W. Biederman" ebiederm@xmission.com Cc: Arnd Bergmann arnd@arndb.de Cc: linux-doc@vger.kernel.org Signed-off-by: Kees Cook keescook@chromium.org Signed-off-by: Eric Biggers ebiggers@google.com --- Documentation/admin-guide/sysctl/kernel.rst | 5 +++-- kernel/exit.c | 2 +- 2 files changed, 4 insertions(+), 3 deletions(-)
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index b6e68d6f297e5..d6f1d3892e71e 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -675,8 +675,9 @@ oops_limit ==========
Number of kernel oopses after which the kernel should panic when -``panic_on_oops`` is not set. Setting this to 0 or 1 has the same effect -as setting ``panic_on_oops=1``. +``panic_on_oops`` is not set. Setting this to 0 disables checking +the count. Setting this to 1 has the same effect as setting +``panic_on_oops=1``. The default value is 10000.
osrelease, ostype & version diff --git a/kernel/exit.c b/kernel/exit.c index f68a9c6adfc9c..f6c85101dba0f 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -941,7 +941,7 @@ void __noreturn make_task_dead(int signr) * To make sure this can't happen, place an upper bound on how often the * kernel may oops without panic(). */ - if (atomic_inc_return(&oops_count) >= READ_ONCE(oops_limit)) + if (atomic_inc_return(&oops_count) >= READ_ONCE(oops_limit) && oops_limit) panic("Oopsed too often (kernel.oops_limit is %d)", oops_limit);
do_exit(signr);
From: Kees Cook keescook@chromium.org
commit 79cc1ba7badf9e7a12af99695a557e9ce27ee967 upstream.
Several run-time checkers (KASAN, UBSAN, KFENCE, KCSAN, sched) roll their own warnings, and each check "panic_on_warn". Consolidate this into a single function so that future instrumentation can be added in a single location.
Cc: Marco Elver elver@google.com Cc: Dmitry Vyukov dvyukov@google.com Cc: Ingo Molnar mingo@redhat.com Cc: Peter Zijlstra peterz@infradead.org Cc: Juri Lelli juri.lelli@redhat.com Cc: Vincent Guittot vincent.guittot@linaro.org Cc: Dietmar Eggemann dietmar.eggemann@arm.com Cc: Steven Rostedt rostedt@goodmis.org Cc: Ben Segall bsegall@google.com Cc: Mel Gorman mgorman@suse.de Cc: Daniel Bristot de Oliveira bristot@redhat.com Cc: Valentin Schneider vschneid@redhat.com Cc: Andrey Ryabinin ryabinin.a.a@gmail.com Cc: Alexander Potapenko glider@google.com Cc: Andrey Konovalov andreyknvl@gmail.com Cc: Vincenzo Frascino vincenzo.frascino@arm.com Cc: Andrew Morton akpm@linux-foundation.org Cc: David Gow davidgow@google.com Cc: tangmeng tangmeng@uniontech.com Cc: Jann Horn jannh@google.com Cc: Shuah Khan skhan@linuxfoundation.org Cc: Petr Mladek pmladek@suse.com Cc: "Paul E. McKenney" paulmck@kernel.org Cc: Sebastian Andrzej Siewior bigeasy@linutronix.de Cc: "Guilherme G. Piccoli" gpiccoli@igalia.com Cc: Tiezhu Yang yangtiezhu@loongson.cn Cc: kasan-dev@googlegroups.com Cc: linux-mm@kvack.org Reviewed-by: Luis Chamberlain mcgrof@kernel.org Signed-off-by: Kees Cook keescook@chromium.org Reviewed-by: Marco Elver elver@google.com Reviewed-by: Andrey Konovalov andreyknvl@gmail.com Link: https://lore.kernel.org/r/20221117234328.594699-4-keescook@chromium.org Signed-off-by: Eric Biggers ebiggers@google.com --- include/linux/panic.h | 1 + kernel/kcsan/report.c | 3 +-- kernel/panic.c | 9 +++++++-- kernel/sched/core.c | 3 +-- lib/ubsan.c | 3 +-- mm/kasan/report.c | 4 ++-- mm/kfence/report.c | 3 +-- 7 files changed, 14 insertions(+), 12 deletions(-)
diff --git a/include/linux/panic.h b/include/linux/panic.h index e71161da69c4b..8eb5897c164fc 100644 --- a/include/linux/panic.h +++ b/include/linux/panic.h @@ -11,6 +11,7 @@ extern long (*panic_blink)(int state); __printf(1, 2) void panic(const char *fmt, ...) __noreturn __cold; void nmi_panic(struct pt_regs *regs, const char *msg); +void check_panic_on_warn(const char *origin); extern void oops_enter(void); extern void oops_exit(void); extern bool oops_may_print(void); diff --git a/kernel/kcsan/report.c b/kernel/kcsan/report.c index 21137929d4283..b88d5d5f29e48 100644 --- a/kernel/kcsan/report.c +++ b/kernel/kcsan/report.c @@ -432,8 +432,7 @@ static void print_report(enum kcsan_value_change value_change, dump_stack_print_info(KERN_DEFAULT); pr_err("==================================================================\n");
- if (panic_on_warn) - panic("panic_on_warn set ...\n"); + check_panic_on_warn("KCSAN"); }
static void release_report(unsigned long *flags, struct other_info *other_info) diff --git a/kernel/panic.c b/kernel/panic.c index 0b560312878c5..bf0324941e433 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -193,6 +193,12 @@ static void panic_print_sys_info(void) ftrace_dump(DUMP_ALL); }
+void check_panic_on_warn(const char *origin) +{ + if (panic_on_warn) + panic("%s: panic_on_warn set ...\n", origin); +} + /** * panic - halt the system * @fmt: The text string to print @@ -628,8 +634,7 @@ void __warn(const char *file, int line, void *caller, unsigned taint, if (regs) show_regs(regs);
- if (panic_on_warn) - panic("panic_on_warn set ...\n"); + check_panic_on_warn("kernel");
if (!regs) dump_stack(); diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 2bd5e235d0781..c1458fa8beb3e 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5560,8 +5560,7 @@ static noinline void __schedule_bug(struct task_struct *prev) pr_err("Preemption disabled at:"); print_ip_sym(KERN_ERR, preempt_disable_ip); } - if (panic_on_warn) - panic("scheduling while atomic\n"); + check_panic_on_warn("scheduling while atomic");
dump_stack(); add_taint(TAINT_WARN, LOCKDEP_STILL_OK); diff --git a/lib/ubsan.c b/lib/ubsan.c index 36bd75e334263..60c7099857a05 100644 --- a/lib/ubsan.c +++ b/lib/ubsan.c @@ -154,8 +154,7 @@ static void ubsan_epilogue(void)
current->in_ubsan--;
- if (panic_on_warn) - panic("panic_on_warn set ...\n"); + check_panic_on_warn("UBSAN"); }
void __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs) diff --git a/mm/kasan/report.c b/mm/kasan/report.c index bf17704b302fc..887af873733bc 100644 --- a/mm/kasan/report.c +++ b/mm/kasan/report.c @@ -117,8 +117,8 @@ static void end_report(unsigned long *flags, unsigned long addr) pr_err("==================================================================\n"); add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); spin_unlock_irqrestore(&report_lock, *flags); - if (panic_on_warn && !test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags)) - panic("panic_on_warn set ...\n"); + if (!test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags)) + check_panic_on_warn("KASAN"); if (kasan_arg_fault == KASAN_ARG_FAULT_PANIC) panic("kasan.fault=panic set ...\n"); kasan_enable_current(); diff --git a/mm/kfence/report.c b/mm/kfence/report.c index 37e140e7f201e..cbd9456359b96 100644 --- a/mm/kfence/report.c +++ b/mm/kfence/report.c @@ -267,8 +267,7 @@ void kfence_report_error(unsigned long address, bool is_write, struct pt_regs *r
lockdep_on();
- if (panic_on_warn) - panic("panic_on_warn set ...\n"); + check_panic_on_warn("KFENCE");
/* We encountered a memory safety error, taint the kernel! */ add_taint(TAINT_BAD_PAGE, LOCKDEP_STILL_OK);
From: Kees Cook keescook@chromium.org
commit 9fc9e278a5c0b708eeffaf47d6eb0c82aa74ed78 upstream.
Like oops_limit, add warn_limit for limiting the number of warnings when panic_on_warn is not set.
Cc: Jonathan Corbet corbet@lwn.net Cc: Andrew Morton akpm@linux-foundation.org Cc: Baolin Wang baolin.wang@linux.alibaba.com Cc: "Jason A. Donenfeld" Jason@zx2c4.com Cc: Eric Biggers ebiggers@google.com Cc: Huang Ying ying.huang@intel.com Cc: Petr Mladek pmladek@suse.com Cc: tangmeng tangmeng@uniontech.com Cc: "Guilherme G. Piccoli" gpiccoli@igalia.com Cc: Tiezhu Yang yangtiezhu@loongson.cn Cc: Sebastian Andrzej Siewior bigeasy@linutronix.de Cc: linux-doc@vger.kernel.org Reviewed-by: Luis Chamberlain mcgrof@kernel.org Signed-off-by: Kees Cook keescook@chromium.org Link: https://lore.kernel.org/r/20221117234328.594699-5-keescook@chromium.org Signed-off-by: Eric Biggers ebiggers@google.com --- Documentation/admin-guide/sysctl/kernel.rst | 10 ++++++++++ kernel/panic.c | 14 ++++++++++++++ 2 files changed, 24 insertions(+)
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index d6f1d3892e71e..48b91c485c993 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -1494,6 +1494,16 @@ entry will default to 2 instead of 0. 2 Unprivileged calls to ``bpf()`` are disabled = =============================================================
+ +warn_limit +========== + +Number of kernel warnings after which the kernel should panic when +``panic_on_warn`` is not set. Setting this to 0 disables checking +the warning count. Setting this to 1 has the same effect as setting +``panic_on_warn=1``. The default value is 0. + + watchdog ========
diff --git a/kernel/panic.c b/kernel/panic.c index bf0324941e433..604d7ad77042e 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -57,6 +57,7 @@ bool crash_kexec_post_notifiers; int panic_on_warn __read_mostly; unsigned long panic_on_taint; bool panic_on_taint_nousertaint = false; +static unsigned int warn_limit __read_mostly;
int panic_timeout = CONFIG_PANIC_TIMEOUT; EXPORT_SYMBOL_GPL(panic_timeout); @@ -86,6 +87,13 @@ static struct ctl_table kern_panic_table[] = { .extra2 = SYSCTL_ONE, }, #endif + { + .procname = "warn_limit", + .data = &warn_limit, + .maxlen = sizeof(warn_limit), + .mode = 0644, + .proc_handler = proc_douintvec, + }, { } };
@@ -195,8 +203,14 @@ static void panic_print_sys_info(void)
void check_panic_on_warn(const char *origin) { + static atomic_t warn_count = ATOMIC_INIT(0); + if (panic_on_warn) panic("%s: panic_on_warn set ...\n", origin); + + if (atomic_inc_return(&warn_count) >= READ_ONCE(warn_limit) && warn_limit) + panic("%s: system warned too often (kernel.warn_limit is %d)", + origin, warn_limit); }
/**
From: Kees Cook keescook@chromium.org
commit 8b05aa26336113c4cea25f1c333ee8cd4fc212a6 upstream.
Since Warn count is now tracked and is a fairly interesting signal, add the entry /sys/kernel/warn_count to expose it to userspace.
Cc: Petr Mladek pmladek@suse.com Cc: Andrew Morton akpm@linux-foundation.org Cc: tangmeng tangmeng@uniontech.com Cc: "Guilherme G. Piccoli" gpiccoli@igalia.com Cc: Sebastian Andrzej Siewior bigeasy@linutronix.de Cc: Tiezhu Yang yangtiezhu@loongson.cn Reviewed-by: Luis Chamberlain mcgrof@kernel.org Signed-off-by: Kees Cook keescook@chromium.org Link: https://lore.kernel.org/r/20221117234328.594699-6-keescook@chromium.org Signed-off-by: Eric Biggers ebiggers@google.com --- .../ABI/testing/sysfs-kernel-warn_count | 6 +++++ kernel/panic.c | 22 +++++++++++++++++-- 2 files changed, 26 insertions(+), 2 deletions(-) create mode 100644 Documentation/ABI/testing/sysfs-kernel-warn_count
diff --git a/Documentation/ABI/testing/sysfs-kernel-warn_count b/Documentation/ABI/testing/sysfs-kernel-warn_count new file mode 100644 index 0000000000000..08f083d2fd51b --- /dev/null +++ b/Documentation/ABI/testing/sysfs-kernel-warn_count @@ -0,0 +1,6 @@ +What: /sys/kernel/oops_count +Date: November 2022 +KernelVersion: 6.2.0 +Contact: Linux Kernel Hardening List linux-hardening@vger.kernel.org +Description: + Shows how many times the system has Warned since last boot. diff --git a/kernel/panic.c b/kernel/panic.c index 604d7ad77042e..4aef355e9a5d1 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -32,6 +32,7 @@ #include <linux/bug.h> #include <linux/ratelimit.h> #include <linux/debugfs.h> +#include <linux/sysfs.h> #include <asm/sections.h>
#define PANIC_TIMER_STEP 100 @@ -105,6 +106,25 @@ static __init int kernel_panic_sysctls_init(void) late_initcall(kernel_panic_sysctls_init); #endif
+static atomic_t warn_count = ATOMIC_INIT(0); + +#ifdef CONFIG_SYSFS +static ssize_t warn_count_show(struct kobject *kobj, struct kobj_attribute *attr, + char *page) +{ + return sysfs_emit(page, "%d\n", atomic_read(&warn_count)); +} + +static struct kobj_attribute warn_count_attr = __ATTR_RO(warn_count); + +static __init int kernel_panic_sysfs_init(void) +{ + sysfs_add_file_to_group(kernel_kobj, &warn_count_attr.attr, NULL); + return 0; +} +late_initcall(kernel_panic_sysfs_init); +#endif + static long no_blink(int state) { return 0; @@ -203,8 +223,6 @@ static void panic_print_sys_info(void)
void check_panic_on_warn(const char *origin) { - static atomic_t warn_count = ATOMIC_INIT(0); - if (panic_on_warn) panic("%s: panic_on_warn set ...\n", origin);
From: Kees Cook keescook@chromium.org
commit 00dd027f721e0458418f7750d8a5a664ed3e5994 upstream.
Running "make htmldocs" shows that "/sys/kernel/oops_count" was duplicated. This should have been "warn_count":
Warning: /sys/kernel/oops_count is defined 2 times: ./Documentation/ABI/testing/sysfs-kernel-warn_count:0 ./Documentation/ABI/testing/sysfs-kernel-oops_count:0
Fix the typo.
Reported-by: kernel test robot lkp@intel.com Link: https://lore.kernel.org/linux-doc/202212110529.A3Qav8aR-lkp@intel.com Fixes: 8b05aa263361 ("panic: Expose "warn_count" to sysfs") Cc: linux-hardening@vger.kernel.org Signed-off-by: Kees Cook keescook@chromium.org Signed-off-by: Eric Biggers ebiggers@google.com --- Documentation/ABI/testing/sysfs-kernel-warn_count | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/Documentation/ABI/testing/sysfs-kernel-warn_count b/Documentation/ABI/testing/sysfs-kernel-warn_count index 08f083d2fd51b..90a029813717d 100644 --- a/Documentation/ABI/testing/sysfs-kernel-warn_count +++ b/Documentation/ABI/testing/sysfs-kernel-warn_count @@ -1,4 +1,4 @@ -What: /sys/kernel/oops_count +What: /sys/kernel/warn_count Date: November 2022 KernelVersion: 6.2.0 Contact: Linux Kernel Hardening List linux-hardening@vger.kernel.org
From: Kees Cook keescook@chromium.org
commit 7535b832c6399b5ebfc5b53af5c51dd915ee2538 upstream.
Use a temporary variable to take full advantage of READ_ONCE() behavior. Without this, the report (and even the test) might be out of sync with the initial test.
Reported-by: Peter Zijlstra peterz@infradead.org Link: https://lore.kernel.org/lkml/Y5x7GXeluFmZ8E0E@hirez.programming.kicks-ass.ne... Fixes: 9fc9e278a5c0 ("panic: Introduce warn_limit") Fixes: d4ccd54d28d3 ("exit: Put an upper limit on how often we can oops") Cc: "Eric W. Biederman" ebiederm@xmission.com Cc: Jann Horn jannh@google.com Cc: Arnd Bergmann arnd@arndb.de Cc: Petr Mladek pmladek@suse.com Cc: Andrew Morton akpm@linux-foundation.org Cc: Luis Chamberlain mcgrof@kernel.org Cc: Marco Elver elver@google.com Cc: tangmeng tangmeng@uniontech.com Cc: Sebastian Andrzej Siewior bigeasy@linutronix.de Cc: Tiezhu Yang yangtiezhu@loongson.cn Signed-off-by: Kees Cook keescook@chromium.org Signed-off-by: Eric Biggers ebiggers@google.com --- kernel/exit.c | 6 ++++-- kernel/panic.c | 7 +++++-- 2 files changed, 9 insertions(+), 4 deletions(-)
diff --git a/kernel/exit.c b/kernel/exit.c index f6c85101dba0f..80efdfda6662b 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -930,6 +930,7 @@ void __noreturn make_task_dead(int signr) * Take the task off the cpu after something catastrophic has * happened. */ + unsigned int limit;
/* * Every time the system oopses, if the oops happens while a reference @@ -941,8 +942,9 @@ void __noreturn make_task_dead(int signr) * To make sure this can't happen, place an upper bound on how often the * kernel may oops without panic(). */ - if (atomic_inc_return(&oops_count) >= READ_ONCE(oops_limit) && oops_limit) - panic("Oopsed too often (kernel.oops_limit is %d)", oops_limit); + limit = READ_ONCE(oops_limit); + if (atomic_inc_return(&oops_count) >= limit && limit) + panic("Oopsed too often (kernel.oops_limit is %d)", limit);
do_exit(signr); } diff --git a/kernel/panic.c b/kernel/panic.c index 4aef355e9a5d1..47933d4c769b6 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -223,12 +223,15 @@ static void panic_print_sys_info(void)
void check_panic_on_warn(const char *origin) { + unsigned int limit; + if (panic_on_warn) panic("%s: panic_on_warn set ...\n", origin);
- if (atomic_inc_return(&warn_count) >= READ_ONCE(warn_limit) && warn_limit) + limit = READ_ONCE(warn_limit); + if (atomic_inc_return(&warn_count) >= limit && limit) panic("%s: system warned too often (kernel.warn_limit is %d)", - origin, warn_limit); + origin, limit); }
/**
On Tue, Jan 24, 2023 at 10:50:50AM -0800, Eric Biggers wrote:
This series backports the patchset "exit: Put an upper limit on how often we can oops" (https://lore.kernel.org/linux-mm/20221117233838.give.484-kees@kernel.org/T/#...) to 5.15, as recommended at https://googleprojectzero.blogspot.com/2023/01/exploiting-null-dereferences-...
I've queued up this and the 5.10 backport, thanks!
linux-stable-mirror@lists.linaro.org
-
Eric Biggers -
Harshit Mogalapalli -
Sasha Levin