[ 01/48] x86/asm/traps: Disable tracing and kprobes in fixup_bad_iret and sync_regs

[Willy Tarreau]

2.6.32-longterm review patch.  If anyone has any objections, please let me know.

------------------

From: Andy Lutomirski <luto@xxxxxxxxxxxxxx>

commit 7ddc6a2199f1da405a2fb68c40db8899b1a8cd87 upstream.

These functions can be executed on the int3 stack, so kprobes
are dangerous. Tracing is probably a bad idea, too.

Fixes: b645af2d5905 ("x86_64, traps: Rework bad_iret")
Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Link: http://lkml.kernel.org/r/50e33d26adca60816f3ba968875801652507d0c4.1416870125.git.luto@xxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
[bwh: Backported to 3.2:
 - Use __kprobes instead of NOKPROBE_SYMBOL()
 - Don't use __visible]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
(cherry picked from commit 8ea4c465ecb59846abed3d000d64b21b8e31aeb0)

Signed-off-by: Willy Tarreau <w@xxxxxx>
---
 arch/x86/kernel/traps.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 8a39a6c..b999043 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -493,7 +493,7 @@ dotraplinkage void __kprobes do_int3(struct pt_regs *regs, long error_code)
  * for scheduling or signal handling. The actual stack switch is done in
  * entry.S
  */
-asmlinkage __kprobes struct pt_regs *sync_regs(struct pt_regs *eregs)
+asmlinkage notrace __kprobes struct pt_regs *sync_regs(struct pt_regs *eregs)
 {
 	struct pt_regs *regs = eregs;
 	/* Did already sync */
@@ -518,7 +518,7 @@ struct bad_iret_stack {
 	struct pt_regs regs;
 };
 
-asmlinkage
+asmlinkage notrace __kprobes
 struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s)
 {
 	/*
-- 
1.7.12.2.21.g234cd45.dirty



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