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[PATCH v8 1/8] softirq: reorder trace_softirqs_on to prevent lockdep splat

by Joel Fernandes

From: "Joel Fernandes (Google)" <joel(a)joelfernandes.org> I'm able to reproduce a lockdep splat with config options: CONFIG_PROVE_LOCKING=y, CONFIG_DEBUG_LOCK_ALLOC=y and CONFIG_PREEMPTIRQ_EVENTS=y $ echo 1 > /d/tracing/events/preemptirq/preempt_enable/enable [ 26.112609] DEBUG_LOCKS_WARN_ON(current->softirqs_enabled) [ 26.112636] WARNING: CPU: 0 PID: 118 at kernel/locking/lockdep.c:3854 [...] [ 26.144229] Call Trace: [ 26.144926] <IRQ> [ 26.145506] lock_acquire+0x55/0x1b0 [ 26.146499] ? __do_softirq+0x46f/0x4d9 [ 26.147571] ? __do_softirq+0x46f/0x4d9 [ 26.148646] trace_preempt_on+0x8f/0x240 [ 26.149744] ? trace_preempt_on+0x4d/0x240 [ 26.150862] ? __do_softirq+0x46f/0x4d9 [ 26.151930] preempt_count_sub+0x18a/0x1a0 [ 26.152985] __do_softirq+0x46f/0x4d9 [ 26.153937] irq_exit+0x68/0xe0 [ 26.154755] smp_apic_timer_interrupt+0x271/0x280 [ 26.156056] apic_timer_interrupt+0xf/0x20 [ 26.157105] </IRQ> The issue was this: preempt_count = 1 << SOFTIRQ_SHIFT __local_bh_enable(cnt = 1 << SOFTIRQ_SHIFT) { if (softirq_count() == (cnt && SOFTIRQ_MASK)) { trace_softirqs_on() { current->softirqs_enabled = 1; } } preempt_count_sub(cnt) { trace_preempt_on() { tracepoint() { rcu_read_lock_sched() { // jumps into lockdep Where preempt_count still has softirqs disabled, but current->softirqs_enabled is true, and we get a splat. Cc: stable(a)vger.kernel.org Reviewed-by: Steven Rostedt (VMware) <rostedt(a)goodmis.org> Fixes: d59158162e032 ("tracing: Add support for preempt and irq enable/disable events") Signed-off-by: Joel Fernandes (Google) <joel(a)joelfernandes.org> --- kernel/softirq.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/kernel/softirq.c b/kernel/softirq.c index 177de3640c78..8a040bcaa033 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -139,9 +139,13 @@ static void __local_bh_enable(unsigned int cnt) { lockdep_assert_irqs_disabled(); + if (preempt_count() == cnt) + trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip()); + if (softirq_count() == (cnt & SOFTIRQ_MASK)) trace_softirqs_on(_RET_IP_); - preempt_count_sub(cnt); + + __preempt_count_sub(cnt); } /* -- 2.17.0.921.gf22659ad46-goog

7 years, 6 months

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+ ocfs2-fix-a-misuse-a-of-brelse-after-failing-ocfs2_check_dir_entry.patch added to -mm tree

by akpm＠linux-foundation.org

The patch titled Subject: ocfs2: fix a misuse a of brelse after failing ocfs2_check_dir_entry has been added to the -mm tree. Its filename is ocfs2-fix-a-misuse-a-of-brelse-after-failing-ocfs2_check_dir_entry.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/ocfs2-fix-a-misuse-a-of-brelse-aft… and later at http://ozlabs.org/~akpm/mmotm/broken-out/ocfs2-fix-a-misuse-a-of-brelse-aft… Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Changwei Ge <ge.changwei(a)h3c.com> Subject: ocfs2: fix a misuse a of brelse after failing ocfs2_check_dir_entry Somehow, file system metadata was corrupted, which causes ocfs2_check_dir_entry() to fail in function ocfs2_dir_foreach_blk_el(). According to the original design intention, if above happens we should skip the problematic block and continue to retrieve dir entry. But there is obviouse misuse of brelse around related code. After failure of ocfs2_check_dir_entry(), currunt code just moves to next position and uses the problematic buffer head again and again during which the problematic buffer head is released for multiple times. I suppose, this a serious issue which is long-lived in ocfs2. This may cause other file systems which is also used in a the same host insane. So we should also consider about bakcporting this patch into linux -stable. Link: http://lkml.kernel.org/r/HK2PR06MB045211675B43EED794E597B6D56E0@HK2PR06MB04… Signed-off-by: Changwei Ge <ge.changwei(a)h3c.com> Suggested-by: Changkuo Shi <shi.changkuo(a)h3c.com> Cc: Mark Fasheh <mark(a)fasheh.com> Cc: Joel Becker <jlbec(a)evilplan.org> Cc: Junxiao Bi <junxiao.bi(a)oracle.com> Cc: Joseph Qi <jiangqi903(a)gmail.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- fs/ocfs2/dir.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff -puN fs/ocfs2/dir.c~ocfs2-fix-a-misuse-a-of-brelse-after-failing-ocfs2_check_dir_entry fs/ocfs2/dir.c --- a/fs/ocfs2/dir.c~ocfs2-fix-a-misuse-a-of-brelse-after-failing-ocfs2_check_dir_entry +++ a/fs/ocfs2/dir.c @@ -1897,8 +1897,7 @@ static int ocfs2_dir_foreach_blk_el(stru /* On error, skip the f_pos to the next block. */ ctx->pos = (ctx->pos | (sb->s_blocksize - 1)) + 1; - brelse(bh); - continue; + break; } if (le64_to_cpu(de->inode)) { unsigned char d_type = DT_UNKNOWN; _ Patches currently in -mm which might be from ge.changwei(a)h3c.com are ocfs2-fix-a-misuse-a-of-brelse-after-failing-ocfs2_check_dir_entry.patch ocfs2-dont-put-and-assign-null-to-bh-allocated-outside.patch ocfs2-dont-use-iocb-when-eiocbqueued-returns.patch

7 years, 6 months

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[PATCH] fs/binfmt_misc.c: do not allow offset overflow

by Thadeu Lima de Souza Cascardo

It's possible to overflow the offset to get a negative value, which might crash the system, or possibly leak kernel data. Here is a crash log when using 2500000000 as offset: [ 6050.251552] BUG: unable to handle kernel paging request at ffff989cfd6edca0 [ 6050.252053] IP: load_misc_binary+0x22b/0x470 [binfmt_misc] [ 6050.252053] PGD 1ef3e067 P4D 1ef3e067 PUD 0 [ 6050.252053] Oops: 0000 [#1] SMP NOPTI [ 6050.252053] Modules linked in: binfmt_misc kvm_intel ppdev kvm irqbypass joydev input_leds serio_raw mac_hid parport_pc qemu_fw_cfg parpy [ 6050.252053] CPU: 0 PID: 2499 Comm: bash Not tainted 4.15.0-22-generic #24-Ubuntu [ 6050.252053] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.1-1 04/01/2014 [ 6050.252053] RIP: 0010:load_misc_binary+0x22b/0x470 [binfmt_misc] [ 6050.252053] RSP: 0018:ffffb6e383017e18 EFLAGS: 00010202 [ 6050.252053] RAX: 0000000000000003 RBX: ffff989d74a47100 RCX: ffff989cfd6edca0 [ 6050.252053] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff989d7d2e95e5 [ 6050.252053] RBP: ffffb6e383017e48 R08: 0000000000000001 R09: 0000000000000000 [ 6050.252053] R10: 0000000000000000 R11: fefefefefefefeff R12: 0000000000000001 [ 6050.252053] R13: ffff989d7d2e9580 R14: 0000000000000000 R15: ffffffffc0592160 [ 6050.252053] FS: 00007fa424c89740(0000) GS:ffff989d7fc00000(0000) knlGS:0000000000000000 [ 6050.252053] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 6050.252053] CR2: ffff989cfd6edca0 CR3: 000000003db08000 CR4: 00000000000006f0 [ 6050.252053] Call Trace: [ 6050.252053] search_binary_handler+0x97/0x1d0 [ 6050.252053] do_execveat_common.isra.34+0x667/0x810 [ 6050.252053] SyS_execve+0x31/0x40 [ 6050.252053] do_syscall_64+0x73/0x130 [ 6050.252053] entry_SYSCALL_64_after_hwframe+0x3d/0xa2 Use kstrtoint instead of simple_strtoul. It will work as the code already set the delimiter byte to '\0' and we only do it when the field is not empty. Tested with offsets -1, 2500000000, UINT_MAX and INT_MAX. Also tested with examples documented at Documentation/admin-guide/binfmt-misc.rst and other registrations from packages on Ubuntu. Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo(a)canonical.com> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable(a)vger.kernel.org --- fs/binfmt_misc.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c index a41b48f82a70..4de191563261 100644 --- a/fs/binfmt_misc.c +++ b/fs/binfmt_misc.c @@ -387,8 +387,13 @@ static Node *create_entry(const char __user *buffer, size_t count) s = strchr(p, del); if (!s) goto einval; - *s++ = '\0'; - e->offset = simple_strtoul(p, &p, 10); + *s = '\0'; + if (p != s) { + int r = kstrtoint(p, 10, &e->offset); + if (r != 0 || e->offset < 0) + goto einval; + } + p = s; if (*p++) goto einval; pr_debug("register: offset: %#x\n", e->offset); @@ -428,7 +433,8 @@ static Node *create_entry(const char __user *buffer, size_t count) if (e->mask && string_unescape_inplace(e->mask, UNESCAPE_HEX) != e->size) goto einval; - if (e->size + e->offset > BINPRM_BUF_SIZE) + if (e->size > BINPRM_BUF_SIZE || + BINPRM_BUF_SIZE - e->size < e->offset) goto einval; pr_debug("register: magic/mask length: %i\n", e->size); if (USE_DEBUG) { -- 2.17.0

7 years, 6 months

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[merged] kasan-fix-memory-hotplug-during-boot.patch removed from -mm tree

by akpm＠linux-foundation.org

The patch titled Subject: kasan: fix memory hotplug during boot has been removed from the -mm tree. Its filename was kasan-fix-memory-hotplug-during-boot.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: David Hildenbrand <david(a)redhat.com> Subject: kasan: fix memory hotplug during boot Using module_init() is wrong. E.g. ACPI adds and onlines memory before our memory notifier gets registered. This makes sure that ACPI memory detected during boot up will not result in a kernel crash. Easily reproducible with QEMU, just specify a DIMM when starting up. Link: http://lkml.kernel.org/r/20180522100756.18478-3-david@redhat.com Fixes: 786a8959912e ("kasan: disable memory hotplug") Signed-off-by: David Hildenbrand <david(a)redhat.com> Acked-by: Andrey Ryabinin <aryabinin(a)virtuozzo.com> Cc: Alexander Potapenko <glider(a)google.com> Cc: Dmitry Vyukov <dvyukov(a)google.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/kasan/kasan.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff -puN mm/kasan/kasan.c~kasan-fix-memory-hotplug-during-boot mm/kasan/kasan.c --- a/mm/kasan/kasan.c~kasan-fix-memory-hotplug-during-boot +++ a/mm/kasan/kasan.c @@ -898,5 +898,5 @@ static int __init kasan_memhotplug_init( return 0; } -module_init(kasan_memhotplug_init); +core_initcall(kasan_memhotplug_init); #endif _ Patches currently in -mm which might be from david(a)redhat.com are

7 years, 6 months

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[merged] kasan-free-allocated-shadow-memory-on-mem_cancel_online.patch removed from -mm tree

by akpm＠linux-foundation.org

The patch titled Subject: kasan: free allocated shadow memory on MEM_CANCEL_ONLINE has been removed from the -mm tree. Its filename was kasan-free-allocated-shadow-memory-on-mem_cancel_online.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: David Hildenbrand <david(a)redhat.com> Subject: kasan: free allocated shadow memory on MEM_CANCEL_ONLINE We have to free memory again when we cancel onlining, otherwise a later onlining attempt will fail. Link: http://lkml.kernel.org/r/20180522100756.18478-2-david@redhat.com Fixes: fa69b5989bb0 ("mm/kasan: add support for memory hotplug") Signed-off-by: David Hildenbrand <david(a)redhat.com> Acked-by: Andrey Ryabinin <aryabinin(a)virtuozzo.com> Cc: Alexander Potapenko <glider(a)google.com> Cc: Dmitry Vyukov <dvyukov(a)google.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/kasan/kasan.c | 1 + 1 file changed, 1 insertion(+) diff -puN mm/kasan/kasan.c~kasan-free-allocated-shadow-memory-on-mem_cancel_online mm/kasan/kasan.c --- a/mm/kasan/kasan.c~kasan-free-allocated-shadow-memory-on-mem_cancel_online +++ a/mm/kasan/kasan.c @@ -866,6 +866,7 @@ static int __meminit kasan_mem_notifier( kmemleak_ignore(ret); return NOTIFY_OK; } + case MEM_CANCEL_ONLINE: case MEM_OFFLINE: { struct vm_struct *vm; _ Patches currently in -mm which might be from david(a)redhat.com are

7 years, 6 months

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[merged] kernel-sys-fix-potential-spectre-v1.patch removed from -mm tree

by akpm＠linux-foundation.org

The patch titled Subject: kernel/sys.c: fix potential Spectre v1 issue has been removed from the -mm tree. Its filename was kernel-sys-fix-potential-spectre-v1.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: "Gustavo A. R. Silva" <gustavo(a)embeddedor.com> Subject: kernel/sys.c: fix potential Spectre v1 issue `resource' can be controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability. This issue was detected with the help of Smatch: kernel/sys.c:1474 __do_compat_sys_old_getrlimit() warn: potential spectre issue 'get_current()->signal->rlim' (local cap) kernel/sys.c:1455 __do_sys_old_getrlimit() warn: potential spectre issue 'get_current()->signal->rlim' (local cap) Fix this by sanitizing *resource* before using it to index current->signal->rlim Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1]. [1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2 Link: http://lkml.kernel.org/r/20180515030038.GA11822@embeddedor.com Signed-off-by: Gustavo A. R. Silva <gustavo(a)embeddedor.com> Reviewed-by: Andrew Morton <akpm(a)linux-foundation.org> Cc: Alexei Starovoitov <ast(a)kernel.org> Cc: Dan Williams <dan.j.williams(a)intel.com> Cc: Thomas Gleixner <tglx(a)linutronix.de> Cc: Peter Zijlstra <peterz(a)infradead.org> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- kernel/sys.c | 5 +++++ 1 file changed, 5 insertions(+) diff -puN kernel/sys.c~kernel-sys-fix-potential-spectre-v1 kernel/sys.c --- a/kernel/sys.c~kernel-sys-fix-potential-spectre-v1 +++ a/kernel/sys.c @@ -71,6 +71,9 @@ #include <asm/io.h> #include <asm/unistd.h> +/* Hardening for Spectre-v1 */ +#include <linux/nospec.h> + #include "uid16.h" #ifndef SET_UNALIGN_CTL @@ -1453,6 +1456,7 @@ SYSCALL_DEFINE2(old_getrlimit, unsigned if (resource >= RLIM_NLIMITS) return -EINVAL; + resource = array_index_nospec(resource, RLIM_NLIMITS); task_lock(current->group_leader); x = current->signal->rlim[resource]; task_unlock(current->group_leader); @@ -1472,6 +1476,7 @@ COMPAT_SYSCALL_DEFINE2(old_getrlimit, un if (resource >= RLIM_NLIMITS) return -EINVAL; + resource = array_index_nospec(resource, RLIM_NLIMITS); task_lock(current->group_leader); r = current->signal->rlim[resource]; task_unlock(current->group_leader); _ Patches currently in -mm which might be from gustavo(a)embeddedor.com are

7 years, 6 months

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[merged] mm-kasan-dont-vfree-nonexistent-vm_area.patch removed from -mm tree

by akpm＠linux-foundation.org

The patch titled Subject: mm/kasan: don't vfree() nonexistent vm_area has been removed from the -mm tree. Its filename was mm-kasan-dont-vfree-nonexistent-vm_area.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Andrey Ryabinin <aryabinin(a)virtuozzo.com> Subject: mm/kasan: don't vfree() nonexistent vm_area KASAN uses different routines to map shadow for hot added memory and memory obtained in boot process. Attempt to offline memory onlined by normal boot process leads to this: Trying to vfree() nonexistent vm area (000000005d3b34b9) WARNING: CPU: 2 PID: 13215 at mm/vmalloc.c:1525 __vunmap+0x147/0x190 Call Trace: kasan_mem_notifier+0xad/0xb9 notifier_call_chain+0x166/0x260 __blocking_notifier_call_chain+0xdb/0x140 __offline_pages+0x96a/0xb10 memory_subsys_offline+0x76/0xc0 device_offline+0xb8/0x120 store_mem_state+0xfa/0x120 kernfs_fop_write+0x1d5/0x320 __vfs_write+0xd4/0x530 vfs_write+0x105/0x340 SyS_write+0xb0/0x140 Obviously we can't call vfree() to free memory that wasn't allocated via vmalloc(). Use find_vm_area() to see if we can call vfree(). Unfortunately it's a bit tricky to properly unmap and free shadow allocated during boot, so we'll have to keep it. If memory will come online again that shadow will be reused. Matthew asked: how can you call vfree() on something that isn't a vmalloc address? vfree() is able to free any address returned by __vmalloc_node_range(). And __vmalloc_node_range() gives you any address you ask. It doesn't have to be an address in [VMALLOC_START, VMALLOC_END] range. That's also how the module_alloc()/module_memfree() works on architectures that have designated area for modules. [aryabinin(a)virtuozzo.com: improve comments] Link: http://lkml.kernel.org/r/dabee6ab-3a7a-51cd-3b86-5468718e0390@virtuozzo.com [akpm(a)linux-foundation.org: fix typos, reflow comment] Link: http://lkml.kernel.org/r/20180201163349.8700-1-aryabinin@virtuozzo.com Fixes: fa69b5989bb0 ("mm/kasan: add support for memory hotplug") Signed-off-by: Andrey Ryabinin <aryabinin(a)virtuozzo.com> Reported-by: Paul Menzel <pmenzel+linux-kasan-dev(a)molgen.mpg.de> Cc: Alexander Potapenko <glider(a)google.com> Cc: Dmitry Vyukov <dvyukov(a)google.com> Cc: Matthew Wilcox <willy(a)infradead.org> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/kasan/kasan.c | 63 +++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 61 insertions(+), 2 deletions(-) diff -puN mm/kasan/kasan.c~mm-kasan-dont-vfree-nonexistent-vm_area mm/kasan/kasan.c --- a/mm/kasan/kasan.c~mm-kasan-dont-vfree-nonexistent-vm_area +++ a/mm/kasan/kasan.c @@ -792,6 +792,40 @@ DEFINE_ASAN_SET_SHADOW(f5); DEFINE_ASAN_SET_SHADOW(f8); #ifdef CONFIG_MEMORY_HOTPLUG +static bool shadow_mapped(unsigned long addr) +{ + pgd_t *pgd = pgd_offset_k(addr); + p4d_t *p4d; + pud_t *pud; + pmd_t *pmd; + pte_t *pte; + + if (pgd_none(*pgd)) + return false; + p4d = p4d_offset(pgd, addr); + if (p4d_none(*p4d)) + return false; + pud = pud_offset(p4d, addr); + if (pud_none(*pud)) + return false; + + /* + * We can't use pud_large() or pud_huge(), the first one is + * arch-specific, the last one depends on HUGETLB_PAGE. So let's abuse + * pud_bad(), if pud is bad then it's bad because it's huge. + */ + if (pud_bad(*pud)) + return true; + pmd = pmd_offset(pud, addr); + if (pmd_none(*pmd)) + return false; + + if (pmd_bad(*pmd)) + return true; + pte = pte_offset_kernel(pmd, addr); + return !pte_none(*pte); +} + static int __meminit kasan_mem_notifier(struct notifier_block *nb, unsigned long action, void *data) { @@ -813,6 +847,14 @@ static int __meminit kasan_mem_notifier( case MEM_GOING_ONLINE: { void *ret; + /* + * If shadow is mapped already than it must have been mapped + * during the boot. This could happen if we onlining previously + * offlined memory. + */ + if (shadow_mapped(shadow_start)) + return NOTIFY_OK; + ret = __vmalloc_node_range(shadow_size, PAGE_SIZE, shadow_start, shadow_end, GFP_KERNEL, PAGE_KERNEL, VM_NO_GUARD, @@ -824,8 +866,25 @@ static int __meminit kasan_mem_notifier( kmemleak_ignore(ret); return NOTIFY_OK; } - case MEM_OFFLINE: - vfree((void *)shadow_start); + case MEM_OFFLINE: { + struct vm_struct *vm; + + /* + * shadow_start was either mapped during boot by kasan_init() + * or during memory online by __vmalloc_node_range(). + * In the latter case we can use vfree() to free shadow. + * Non-NULL result of the find_vm_area() will tell us if + * that was the second case. + * + * Currently it's not possible to free shadow mapped + * during boot by kasan_init(). It's because the code + * to do that hasn't been written yet. So we'll just + * leak the memory. + */ + vm = find_vm_area((void *)shadow_start); + if (vm) + vfree((void *)shadow_start); + } } return NOTIFY_OK; _ Patches currently in -mm which might be from aryabinin(a)virtuozzo.com are

7 years, 6 months

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[merged] ipc-shm-fix-shmat-nil-address-after-round-down-when-remapping.patch removed from -mm tree

by akpm＠linux-foundation.org

The patch titled Subject: ipc/shm: fix shmat() nil address after round-down when remapping has been removed from the -mm tree. Its filename was ipc-shm-fix-shmat-nil-address-after-round-down-when-remapping.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Davidlohr Bueso <dave(a)stgolabs.net> Subject: ipc/shm: fix shmat() nil address after round-down when remapping shmat()'s SHM_REMAP option forbids passing a nil address for; this is in fact the very first thing we check for. Andrea reported that for SHM_RND|SHM_REMAP cases we can end up bypassing the initial addr check, but we need to check again if the address was rounded down to nil. As of this patch, such cases will return -EINVAL. Link: http://lkml.kernel.org/r/20180503204934.kk63josdu6u53fbd@linux-n805 Signed-off-by: Davidlohr Bueso <dbueso(a)suse.de> Reported-by: Andrea Arcangeli <aarcange(a)redhat.com> Cc: Joe Lawrence <joe.lawrence(a)redhat.com> Cc: Manfred Spraul <manfred(a)colorfullife.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- ipc/shm.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff -puN ipc/shm.c~ipc-shm-fix-shmat-nil-address-after-round-down-when-remapping ipc/shm.c --- a/ipc/shm.c~ipc-shm-fix-shmat-nil-address-after-round-down-when-remapping +++ a/ipc/shm.c @@ -1363,9 +1363,17 @@ long do_shmat(int shmid, char __user *sh if (addr) { if (addr & (shmlba - 1)) { - if (shmflg & SHM_RND) + if (shmflg & SHM_RND) { addr &= ~(shmlba - 1); /* round down */ - else + + /* + * Ensure that the round-down is non-nil + * when remapping. This can happen for + * cases when addr < shmlba. + */ + if (!addr && (shmflg & SHM_REMAP)) + goto out; + } else #ifndef __ARCH_FORCE_SHMLBA if (addr & ~PAGE_MASK) #endif _ Patches currently in -mm which might be from dave(a)stgolabs.net are ipc-sem-mitigate-semnum-index-against-spectre-v1.patch

7 years, 6 months

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[merged] revert-ipc-shm-fix-shmat-mmap-nil-page-protection.patch removed from -mm tree

by akpm＠linux-foundation.org

The patch titled Subject: Revert "ipc/shm: Fix shmat mmap nil-page protection" has been removed from the -mm tree. Its filename was revert-ipc-shm-fix-shmat-mmap-nil-page-protection.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Davidlohr Bueso <dave(a)stgolabs.net> Subject: Revert "ipc/shm: Fix shmat mmap nil-page protection" Patch series "ipc/shm: shmat() fixes around nil-page". These patches fix two issues reported[1] a while back by Joe and Andrea around how shmat(2) behaves with nil-page. The first reverts a commit that it was incorrectly thought that mapping nil-page (address=0) was a no no with MAP_FIXED. This is not the case, with the exception of SHM_REMAP; which is address in the second patch. I chose two patches because it is easier to backport and it explicitly reverts bogus behaviour. Both patches ought to be in -stable and ltp testcases need updated (the added testcase around the cve can be modified to just test for SHM_RND|SHM_REMAP). [1] lkml.kernel.org/r/20180430172152.nfa564pvgpk3ut7p@linux-n805 This patch (of 2): 95e91b831f87 ("ipc/shm: Fix shmat mmap nil-page protection") worked on the idea that we should not be mapping as root addr=0 and MAP_FIXED. However, it was reported that this scenario is in fact valid, thus making the patch both bogus and breaks userspace as well. For example X11's libint10.so relies on shmat(1, SHM_RND) for lowmem initialization[1]. [1] https://cgit.freedesktop.org/xorg/xserver/tree/hw/xfree86/os-support/linux/… Link: http://lkml.kernel.org/r/20180503203243.15045-2-dave@stgolabs.net Fixes: 95e91b831f87 ("ipc/shm: Fix shmat mmap nil-page protection") Signed-off-by: Davidlohr Bueso <dbueso(a)suse.de> Reported-by: Joe Lawrence <joe.lawrence(a)redhat.com> Reported-by: Andrea Arcangeli <aarcange(a)redhat.com> Cc: Manfred Spraul <manfred(a)colorfullife.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- ipc/shm.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) diff -puN ipc/shm.c~revert-ipc-shm-fix-shmat-mmap-nil-page-protection ipc/shm.c --- a/ipc/shm.c~revert-ipc-shm-fix-shmat-mmap-nil-page-protection +++ a/ipc/shm.c @@ -1363,13 +1363,8 @@ long do_shmat(int shmid, char __user *sh if (addr) { if (addr & (shmlba - 1)) { - /* - * Round down to the nearest multiple of shmlba. - * For sane do_mmap_pgoff() parameters, avoid - * round downs that trigger nil-page and MAP_FIXED. - */ - if ((shmflg & SHM_RND) && addr >= shmlba) - addr &= ~(shmlba - 1); + if (shmflg & SHM_RND) + addr &= ~(shmlba - 1); /* round down */ else #ifndef __ARCH_FORCE_SHMLBA if (addr & ~PAGE_MASK) _ Patches currently in -mm which might be from dave(a)stgolabs.net are ipc-sem-mitigate-semnum-index-against-spectre-v1.patch

7 years, 6 months

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[merged] idr-fix-invalid-ptr-dereference-on-item-delete.patch removed from -mm tree

by akpm＠linux-foundation.org

The patch titled Subject: idr: fix invalid ptr dereference on item delete has been removed from the -mm tree. Its filename was idr-fix-invalid-ptr-dereference-on-item-delete.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Matthew Wilcox <mawilcox(a)microsoft.com> Subject: idr: fix invalid ptr dereference on item delete If the radix tree underlying the IDR happens to be full and we attempt to remove an id which is larger than any id in the IDR, we will call __radix_tree_delete() with an uninitialised 'slot' pointer, at which point anything could happen. This was easiest to hit with a single entry at id 0 and attempting to remove a non-0 id, but it could have happened with 64 entries and attempting to remove an id >= 64. Roman said: The syzcaller test boils down to opening /dev/kvm, creating an eventfd, and calling a couple of KVM ioctls. None of this requires superuser. And the result is dereferencing an uninitialized pointer which is likely a crash. The specific path caught by syzbot is via KVM_HYPERV_EVENTD ioctl which is new in 4.17. But I guess there are other user-triggerable paths, so cc:stable is probably justified. Matthew added: We have around 250 calls to idr_remove() in the kernel today. Many of them pass an ID which is embedded in the object they're removing, so they're safe. Picking a few likely candidates: drivers/firewire/core-cdev.c looks unsafe; the ID comes from an ioctl. drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c is similar drivers/atm/nicstar.c could be taken down by a handcrafted packet Link: http://lkml.kernel.org/r/20180518175025.GD6361@bombadil.infradead.org Fixes: 0a835c4f090a ("Reimplement IDR and IDA using the radix tree") Reported-by: <syzbot+35666cba7f0a337e2e79(a)syzkaller.appspotmail.com> Debugged-by: Roman Kagan <rkagan(a)virtuozzo.com> Signed-off-by: Matthew Wilcox <mawilcox(a)microsoft.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- lib/radix-tree.c | 4 +++- tools/testing/radix-tree/idr-test.c | 7 +++++++ 2 files changed, 10 insertions(+), 1 deletion(-) diff -puN lib/radix-tree.c~idr-fix-invalid-ptr-dereference-on-item-delete lib/radix-tree.c --- a/lib/radix-tree.c~idr-fix-invalid-ptr-dereference-on-item-delete +++ a/lib/radix-tree.c @@ -2034,10 +2034,12 @@ void *radix_tree_delete_item(struct radi unsigned long index, void *item) { struct radix_tree_node *node = NULL; - void __rcu **slot; + void __rcu **slot = NULL; void *entry; entry = __radix_tree_lookup(root, index, &node, &slot); + if (!slot) + return NULL; if (!entry && (!is_idr(root) || node_tag_get(root, node, IDR_FREE, get_slot_offset(node, slot)))) return NULL; diff -puN tools/testing/radix-tree/idr-test.c~idr-fix-invalid-ptr-dereference-on-item-delete tools/testing/radix-tree/idr-test.c --- a/tools/testing/radix-tree/idr-test.c~idr-fix-invalid-ptr-dereference-on-item-delete +++ a/tools/testing/radix-tree/idr-test.c @@ -252,6 +252,13 @@ void idr_checks(void) idr_remove(&idr, 3); idr_remove(&idr, 0); + assert(idr_alloc(&idr, DUMMY_PTR, 0, 0, GFP_KERNEL) == 0); + idr_remove(&idr, 1); + for (i = 1; i < RADIX_TREE_MAP_SIZE; i++) + assert(idr_alloc(&idr, DUMMY_PTR, 0, 0, GFP_KERNEL) == i); + idr_remove(&idr, 1 << 30); + idr_destroy(&idr); + for (i = INT_MAX - 3UL; i < INT_MAX + 1UL; i++) { struct item *item = item_create(i, 0); assert(idr_alloc(&idr, item, i, i + 10, GFP_KERNEL) == i); _ Patches currently in -mm which might be from mawilcox(a)microsoft.com are slab-__gfp_zero-is-incompatible-with-a-constructor.patch s390-use-_refcount-for-pgtables.patch mm-split-page_type-out-from-_mapcount.patch mm-mark-pages-in-use-for-page-tables.patch mm-switch-s_mem-and-slab_cache-in-struct-page.patch mm-move-private-union-within-struct-page.patch mm-move-_refcount-out-of-struct-page-union.patch mm-combine-first-three-unions-in-struct-page.patch mm-use-page-deferred_list.patch mm-move-lru-union-within-struct-page.patch mm-combine-lru-and-main-union-in-struct-page.patch mm-improve-struct-page-documentation.patch mm-add-pt_mm-to-struct-page.patch mm-add-hmm_data-to-struct-page.patch slabslub-remove-rcu_head-size-checks.patch slub-remove-kmem_cache-reserved.patch slub-remove-reserved-file-from-sysfs.patch ida-remove-simple_ida_lock.patch

7 years, 6 months

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