From: Nigel Cunningham <nigel@nigel.suspend2.net>

call_usermodehelper_exec() has an exit path that can leave the
helper_lock() call at the top of the routine unbalanced.  The attached
patch fixes this issue.

Signed-off-by: Nigel Cunningham <nigel@tuxonice.net>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 kernel/kmod.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff -puN kernel/kmod.c~fix-unbalanced-helper_lock-in-kernel-kmodc kernel/kmod.c
--- a/kernel/kmod.c~fix-unbalanced-helper_lock-in-kernel-kmodc
+++ a/kernel/kmod.c
@@ -465,13 +465,16 @@ int call_usermodehelper_exec(struct subp
 	sub_info->wait = wait;
 
 	queue_work(khelper_wq, &sub_info->work);
-	if (wait == UMH_NO_WAIT) /* task has freed sub_info */
-		return 0;
+	if (wait == UMH_NO_WAIT) { /* task has freed sub_info */
+		retval = 0;
+		goto unlock;
+	}
 	wait_for_completion(&done);
 	retval = sub_info->retval;
 
-  out:
+out:
 	call_usermodehelper_freeinfo(sub_info);
+unlock:
 	helper_unlock();
 	return retval;
 }
_