[PATCH] fsnotify: don't put user context if it was never assigned

From: Sasha Levin
Date: Tue Jul 29 2014 - 09:25:32 EST

On some failure paths we may attempt to free user context even
if it wasn't assigned yet. This will cause a NULL ptr deref
and a kernel BUG.

Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
fs/notify/inotify/inotify_fsnotify.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/notify/inotify/inotify_fsnotify.c b/fs/notify/inotify/inotify_fsnotify.c
index 43ab1e1..9c8187e 100644
--- a/fs/notify/inotify/inotify_fsnotify.c
+++ b/fs/notify/inotify/inotify_fsnotify.c
@@ -165,8 +165,10 @@ static void inotify_free_group_priv(struct fsnotify_group *group)
/* ideally the idr is empty and we won't hit the BUG in the callback */
idr_for_each(&group->inotify_data.idr, idr_callback, group);
- atomic_dec(&group->inotify_data.user->inotify_devs);
- free_uid(group->inotify_data.user);
+ if (group->inotify_data.user) {
+ atomic_dec(&group->inotify_data.user->inotify_devs);
+ free_uid(group->inotify_data.user);
+ }

static void inotify_free_event(struct fsnotify_event *fsn_event)

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