6.6-stable review patch. If anyone has any objections, please let me know.
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From: Helge Deller deller@gmx.de
commit 5f74f820f6fc844b95f9e5e406e0a07d97510420 upstream.
Matoro reported various userspace crashes on the parisc platform with kernel 6.6 and bisected it to commit 3033cd430768 ("parisc: Use generic mmap top-down layout and brk randomization").
That commit switched parisc to use the common infrastructure to calculate mmap_base, but missed that the mmap_base() function takes care for architectures where the stack grows downwards only.
Fix the mmap_base() calculation to include the stack-grows-upwards case and thus fix the userspace crashes on parisc.
Link: https://lkml.kernel.org/r/ZVH2qeS1bG7/1J/l@p100 Fixes: 3033cd430768 ("parisc: Use generic mmap top-down layout and brk randomization") Signed-off-by: Helge Deller deller@gmx.de Reported-by: matoro matoro_mailinglist_kernel@matoro.tk Tested-by: matoro matoro_mailinglist_kernel@matoro.tk Cc: stable@vger.kernel.org [6.6+] Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/parisc/Kconfig | 6 +++--- arch/parisc/include/asm/elf.h | 10 +--------- arch/parisc/include/asm/processor.h | 2 ++ arch/parisc/kernel/sys_parisc.c | 2 +- mm/util.c | 10 ++++++++++ 5 files changed, 17 insertions(+), 13 deletions(-)
--- a/arch/parisc/Kconfig +++ b/arch/parisc/Kconfig @@ -138,11 +138,11 @@ config ARCH_MMAP_RND_COMPAT_BITS_MIN default 8
config ARCH_MMAP_RND_BITS_MAX - default 24 if 64BIT - default 17 + default 18 if 64BIT + default 13
config ARCH_MMAP_RND_COMPAT_BITS_MAX - default 17 + default 13
# unless you want to implement ACPI on PA-RISC ... ;-) config PM --- a/arch/parisc/include/asm/elf.h +++ b/arch/parisc/include/asm/elf.h @@ -349,15 +349,7 @@ struct pt_regs; /* forward declaration..
#define ELF_HWCAP 0
-/* Masks for stack and mmap randomization */ -#define BRK_RND_MASK (is_32bit_task() ? 0x07ffUL : 0x3ffffUL) -#define MMAP_RND_MASK (is_32bit_task() ? 0x1fffUL : 0x3ffffUL) -#define STACK_RND_MASK MMAP_RND_MASK - -struct mm_struct; -extern unsigned long arch_randomize_brk(struct mm_struct *); -#define arch_randomize_brk arch_randomize_brk - +#define STACK_RND_MASK 0x7ff /* 8MB of VA */
#define ARCH_HAS_SETUP_ADDITIONAL_PAGES 1 struct linux_binprm; --- a/arch/parisc/include/asm/processor.h +++ b/arch/parisc/include/asm/processor.h @@ -47,6 +47,8 @@
#ifndef __ASSEMBLY__
+struct rlimit; +unsigned long mmap_upper_limit(struct rlimit *rlim_stack); unsigned long calc_max_stack_size(unsigned long stack_max);
/* --- a/arch/parisc/kernel/sys_parisc.c +++ b/arch/parisc/kernel/sys_parisc.c @@ -77,7 +77,7 @@ unsigned long calc_max_stack_size(unsign * indicating that "current" should be used instead of a passed-in * value from the exec bprm as done with arch_pick_mmap_layout(). */ -static unsigned long mmap_upper_limit(struct rlimit *rlim_stack) +unsigned long mmap_upper_limit(struct rlimit *rlim_stack) { unsigned long stack_base;
--- a/mm/util.c +++ b/mm/util.c @@ -414,6 +414,15 @@ static int mmap_is_legacy(struct rlimit
static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack) { +#ifdef CONFIG_STACK_GROWSUP + /* + * For an upwards growing stack the calculation is much simpler. + * Memory for the maximum stack size is reserved at the top of the + * task. mmap_base starts directly below the stack and grows + * downwards. + */ + return PAGE_ALIGN_DOWN(mmap_upper_limit(rlim_stack) - rnd); +#else unsigned long gap = rlim_stack->rlim_cur; unsigned long pad = stack_guard_gap;
@@ -431,6 +440,7 @@ static unsigned long mmap_base(unsigned gap = MAX_GAP;
return PAGE_ALIGN(STACK_TOP - gap - rnd); +#endif }
void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)