From d5a2601734bcc740ee78dc4cb0c56b5687da7bd9 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Fri, 28 Jul 2006 14:44:42 +0200 Subject: [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 --- arch/i386/kernel/time.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/i386/kernel/time.c') diff --git a/arch/i386/kernel/time.c b/arch/i386/kernel/time.c index 8705c0f05788..edd00f6cee37 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; -- cgit v1.2.2