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x86: Add stack top margin for stack overflow checking

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It seems that a margin for stack overflow checking is added to
top of a kernel stack but is not added to IRQ and exception
stacks in stack_overflow_check(). Therefore, the overflows of
IRQ and exception stacks are always detected only after they
actually occurred and data corruption might occur due to them.

This patch adds the margin to top of IRQ and exception stacks
as well as a kernel stack to enhance reliability.

Signed-off-by: Mitsuo Hayasaka <mitsuo.hayasaka.hu@hitachi.com>
Cc: yrl.pp-manager.tt@hitachi.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20111207082910.9847.3359.stgit@ltc219.sdl.hitachi.co.jp
[ removed the #undef - we typically don't do that for uncommon names ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Mitsuo Hayasaka 2011-12-07 17:29:10 +09:00 committed by Ingo Molnar
parent 565cbc3e93
commit d2db661021
1 changed files with 5 additions and 3 deletions
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8
arch/x86/kernel/irq_64.c
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@ -38,6 +38,7 @@ int sysctl_panic_on_stackoverflow;
static inline void stack_overflow_check(struct pt_regs *regs)
{
#ifdef CONFIG_DEBUG_STACKOVERFLOW
#define STACK_TOP_MARGIN 128
struct orig_ist *oist;
u64 irq_stack_top, irq_stack_bottom;
u64 estack_top, estack_bottom;
@ -47,17 +48,18 @@ static inline void stack_overflow_check(struct pt_regs *regs)
return;
if (regs->sp >= curbase + sizeof(struct thread_info) +
sizeof(struct pt_regs) + 128 &&
sizeof(struct pt_regs) + STACK_TOP_MARGIN &&
regs->sp <= curbase + THREAD_SIZE)
return;
irq_stack_top = (u64)__get_cpu_var(irq_stack_union.irq_stack);
irq_stack_top = (u64)__get_cpu_var(irq_stack_union.irq_stack) +
STACK_TOP_MARGIN;
irq_stack_bottom = (u64)__get_cpu_var(irq_stack_ptr);
if (regs->sp >= irq_stack_top && regs->sp <= irq_stack_bottom)
return;
oist = &__get_cpu_var(orig_ist);
estack_top = (u64)oist->ist[0] - EXCEPTION_STKSZ;
estack_top = (u64)oist->ist[0] - EXCEPTION_STKSZ + STACK_TOP_MARGIN;
estack_bottom = (u64)oist->ist[N_EXCEPTION_STACKS - 1];
if (regs->sp >= estack_top && regs->sp <= estack_bottom)
return;