[PATCH] i386: Disallow kprobes on NMI handlers

A kprobe executes IRET early and that could cause NMI recursion and stack
corruption.

Note: This problem was originally spotted and solved by Andi Kleen in the
x86_64 architecture. This patch is an adaption of his patch for i386.

AK: Merged with current code which was a bit different.
AK: Removed printk in nmi handler that shouldn't be there in the first time
AK: Added missing include.
AK: added KPROBES_END

Signed-off-by: Fernando Vazquez <fernando@intellilink.co.jp>
Signed-off-by: Andi Kleen <ak@suse.de>

1 files changed, 2 insertions, 1 deletions

diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S
index dede506e5bd0..0928f70639aa 100644
--- a/arch/i386/kernel/entry.S
+++ b/arch/i386/kernel/entry.S
@@ -729,7 +729,7 @@ KPROBE_END(debug)
  * check whether we got an NMI on the debug path where the debug
  * fault happened on the sysenter path.
  */
-ENTRY(nmi)
+KPROBE_ENTRY(nmi)
         RING0_INT_FRAME
         pushl %eax
         CFI_ADJUST_CFA_OFFSET 4
@@ -805,6 +805,7 @@ nmi_16bit_stack:
         .align 4
         .long 1b,iret_exc
 .previous
+KPROBE_END(nmi)
 
 KPROBE_ENTRY(int3)
         RING0_INT_FRAME