Fix unbalanced helper_lock in kernel/kmod.c

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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 7 deletions

diff --git a/kernel/kmod.c b/kernel/kmod.c
index c6a4f8aebeba..bb7df2a28bd7 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -451,13 +451,11 @@ int call_usermodehelper_exec(struct subprocess_info *sub_info,
                              enum umh_wait wait)
 {
         DECLARE_COMPLETION_ONSTACK(done);
-        int retval;
+        int retval = 0;
 
         helper_lock();
-        if (sub_info->path[0] == '\0') {
-                retval = 0;
+        if (sub_info->path[0] == '\0')
                 goto out;
-        }
 
         if (!khelper_wq || usermodehelper_disabled) {
                 retval = -EBUSY;
@@ -468,13 +466,14 @@ int call_usermodehelper_exec(struct subprocess_info *sub_info,
         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 */
+                goto unlock;
         wait_for_completion(&done);
         retval = sub_info->retval;
 
-  out:
+out:
         call_usermodehelper_freeinfo(sub_info);
+unlock:
         helper_unlock();
         return retval;
 }