Commit 69682b62 authored Nov 29, 2011 by Mitsuo Hayasaka Committed by Ingo Molnar Dec 05, 2011

x86: Add user_mode_vm check in stack_overflow_check



The kernel stack overflow is checked in stack_overflow_check(),
which may wrongly detect the overflow if the stack pointer in
user space points to the kernel stack intentionally or
accidentally. So, the actual overflow is never detected after
this misdetection because WARN_ONCE() is used on the detection
of it.

This patch adds user-mode-vm checking before it to avoid this
problem and bails out early if the user stack is used.

Signed-off-by: Mitsuo Hayasaka <mitsuo.hayasaka.hu@hitachi.com>
Cc: yrl.pp-manager.tt@hitachi.com
Cc: Randy Dunlap <rdunlap@xenotime.net>
Link: http://lkml.kernel.org/r/20111129060821.11076.55315.stgit@ltc219.sdl.hitachi.co.jp


Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>

parent 8e8da023

arch/x86/kernel/irq_64.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -38,6 +38,9 @@ static inline void stack_overflow_check(struct pt_regs *regs)
		#ifdef CONFIG_DEBUG_STACKOVERFLOW
		u64 curbase = (u64)task_stack_page(current);

		if (user_mode_vm(regs))
		return;

		WARN_ONCE(regs->sp >= curbase &&
		regs->sp <= curbase + THREAD_SIZE &&
		regs->sp < curbase + sizeof(struct thread_info) +

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