From c6f6343ea39d7cf825e4a1459330ef7ee5d4b6be Mon Sep 17 00:00:00 2001
From: Sapan Bhatia <gwsapan@gmail.com>
Date: Tue, 9 Apr 2013 11:37:22 -0400
Subject: [PATCH] Possible race condition and consequent crash

---
 procprotect.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/procprotect.c b/procprotect.c
index 2e8cd13..950be09 100644
--- a/procprotect.c
+++ b/procprotect.c
@@ -157,8 +157,12 @@ static int lookup_slow_entry(struct kretprobe_instance *ri, struct pt_regs *regs
 
 static int lookup_slow_ret(struct kretprobe_instance *ri, struct pt_regs *regs)
 {
-    struct procprotect_ctx *ctx = (struct procprotect_ctx *) ri->data;
-    int ret = regs->ax;
+    struct procprotect_ctx *ctx;
+    int ret;
+
+    if (!ri) {/* Race condition?*/ return 0;}
+    ctx = (struct procprotect_ctx *) ri->data;
+    ret = regs->ax;
 
     if (ret==0) {
         /* The kernel is going to honor the request. Here's where we step in */
-- 
2.43.0