From: Andi Kleen Date: Fri, 28 Jul 2006 12:44:42 +0000 (+0200) Subject: [PATCH] i386/x86-64: Add user_mode checks to profile_pc for oprofile X-Git-Tag: v2.6.18-rc3~22 X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=d5a2601734bcc740ee78dc4cb0c56b5687da7bd9;p=linux-2.6-omap-h63xx.git [PATCH] i386/x86-64: Add user_mode checks to profile_pc for oprofile Fixes a obscure user space triggerable crash during oprofiling. Oprofile calls profile_pc from NMIs even when user_mode(regs) is not true and the program counter is inside the kernel lock section. This opens a race - when a user program jumps to a kernel lock address and a NMI happens before the illegal page fault exception is raised and the program has a unmapped esp or ebp then the kernel could oops. NMIs have a higher priority than exceptions so that could happen. Add user_mode checks to i386/x86-64 profile_pc to prevent that. Cc: John Levon Signed-off-by: Andi Kleen Signed-off-by: Linus Torvalds --- diff --git a/arch/i386/kernel/time.c b/arch/i386/kernel/time.c index 8705c0f0578..edd00f6cee3 100644 --- a/arch/i386/kernel/time.c +++ b/arch/i386/kernel/time.c @@ -135,7 +135,7 @@ unsigned long profile_pc(struct pt_regs *regs) { unsigned long pc = instruction_pointer(regs); - if (in_lock_functions(pc)) + if (!user_mode_vm(regs) && in_lock_functions(pc)) return *(unsigned long *)(regs->ebp + 4); return pc; diff --git a/arch/x86_64/kernel/time.c b/arch/x86_64/kernel/time.c index b9ff75992c1..e0341c6808e 100644 --- a/arch/x86_64/kernel/time.c +++ b/arch/x86_64/kernel/time.c @@ -193,7 +193,7 @@ unsigned long profile_pc(struct pt_regs *regs) is just accounted to the spinlock function. Better would be to write these functions in assembler again and check exactly. */ - if (in_lock_functions(pc)) { + if (!user_mode(regs) && in_lock_functions(pc)) { char *v = *(char **)regs->rsp; if ((v >= _stext && v <= _etext) || (v >= _sinittext && v <= _einittext) ||