Commit d5a26017 authored Jul 28, 2006 by Andi Kleen Committed by Linus Torvalds Jul 28, 2006

[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>

parent 5d2edfe0

arch/i386/kernel/time.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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;

arch/x86_64/kernel/time.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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) \|\|