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[PATCH] i386/x86-64: Add user_mode checks to profile_pc for oprofile

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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>
This commit is contained in:
Andi Kleen 2006-07-28 14:44:42 +02:00 committed by Linus Torvalds
parent 5d2edfe004
commit d5a2601734
2 changed files with 2 additions and 2 deletions
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2
arch/i386/kernel/time.c
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@ -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;

2
arch/x86_64/kernel/time.c
View file

@ -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) ||