From 69682b625a043b567873e6cda397969b502f0054 Mon Sep 17 00:00:00 2001 From: Mitsuo Hayasaka <mitsuo.hayasaka.hu@hitachi.com> Date: Tue, 29 Nov 2011 15:08:21 +0900 Subject: [PATCH] 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> --- arch/x86/kernel/irq_64.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/x86/kernel/irq_64.c b/arch/x86/kernel/irq_64.c index acf8fbf8fbda..69bca468c47a 100644 --- a/arch/x86/kernel/irq_64.c +++ b/arch/x86/kernel/irq_64.c @@ -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) +