From d5a2601734bcc740ee78dc4cb0c56b5687da7bd9 Mon Sep 17 00:00:00 2001
From: Andi Kleen <ak@suse.de>
Date: Fri, 28 Jul 2006 14:44:42 +0200
Subject: [PATCH] [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 <levon@movementarian.org>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---
arch/i386/kernel/time.c | 2 +-
arch/x86_64/kernel/time.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
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;
diff --git a/arch/x86_64/kernel/time.c b/arch/x86_64/kernel/time.c
index b9ff75992c16..e0341c6808e5 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) ||
--
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