[PATCH] kprobes: fix bug when probed on task and isr functions

This patch fixes a race condition where in system used to hang or sometime
crash within minutes when kprobes are inserted on ISR routine and a task
routine.

The fix has been stress tested on i386, ia64, pp64 and on x86_64.  To
reproduce the problem insert kprobes on schedule() and do_IRQ() functions
and you should see hang or system crash.

Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Acked-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/arch/x86_64/kernel/kprobes.c b/arch/x86_64/kernel/kprobes.c
index 2d7658fbbb28..df08c43276a0 100644
--- a/arch/x86_64/kernel/kprobes.c
+++ b/arch/x86_64/kernel/kprobes.c
@@ -311,7 +311,8 @@ int __kprobes kprobe_handler(struct pt_regs *regs)
                    Disarm the probe we just hit, and ignore it. */
                 p = get_kprobe(addr);
                 if (p) {
-                        if (kprobe_status == KPROBE_HIT_SS) {
+                        if (kprobe_status == KPROBE_HIT_SS &&
+                                *p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
                                 regs->eflags &= ~TF_MASK;
                                 regs->eflags |= kprobe_saved_rflags;
                                 unlock_kprobes();