x86: Add stack top margin for stack overflow checking (d2db6610) · Commits · 戴 / test

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>

arch/x86/kernel/irq_64.c

+5 −3

Original line number	Diff line number	Diff line
		@@ -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;

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