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Commit d2db6610219cbcadceea6c43ee03d89068b7d759

Authored by Mitsuo Hayasaka
Committed by Ingo Molnar
1 parent 565cbc3e93
Exists in master and in 6 other branches imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-l5.0.0_1.0.0-ga

x86: Add stack top margin for stack overflow checking 

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>

Showing 1 changed file with 5 additions and 3 deletions Side-by-side Diff

arch/x86/kernel/irq_64.c
Diff comments   View file @ d2db661
... ... @@ -38,6 +38,7 @@
38 38 static inline void stack_overflow_check(struct pt_regs *regs)
39 39 {
40 40 #ifdef CONFIG_DEBUG_STACKOVERFLOW
  41 +#define STACK_TOP_MARGIN 128
41 42 struct orig_ist *oist;
42 43 u64 irq_stack_top, irq_stack_bottom;
43 44 u64 estack_top, estack_bottom;
44 45  
45 46  
... ... @@ -47,17 +48,18 @@
47 48 return;
48 49  
49 50 if (regs->sp >= curbase + sizeof(struct thread_info) +
50   - sizeof(struct pt_regs) + 128 &&
  51 + sizeof(struct pt_regs) + STACK_TOP_MARGIN &&
51 52 regs->sp <= curbase + THREAD_SIZE)
52 53 return;
53 54  
54   - irq_stack_top = (u64)__get_cpu_var(irq_stack_union.irq_stack);
  55 + irq_stack_top = (u64)__get_cpu_var(irq_stack_union.irq_stack) +
  56 + STACK_TOP_MARGIN;
55 57 irq_stack_bottom = (u64)__get_cpu_var(irq_stack_ptr);
56 58 if (regs->sp >= irq_stack_top && regs->sp <= irq_stack_bottom)
57 59 return;
58 60  
59 61 oist = &__get_cpu_var(orig_ist);
60   - estack_top = (u64)oist->ist[0] - EXCEPTION_STKSZ;
  62 + estack_top = (u64)oist->ist[0] - EXCEPTION_STKSZ + STACK_TOP_MARGIN;
61 63 estack_bottom = (u64)oist->ist[N_EXCEPTION_STACKS - 1];
62 64 if (regs->sp >= estack_top && regs->sp <= estack_bottom)
63 65 return;