summaryrefslogtreecommitdiff
path: root/fs/notify/notification.c
diff options
context:
space:
mode:
authorJan Kara <jack@suse.cz>2014-08-07 03:03:28 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2014-08-07 05:01:12 +0400
commit5838d4442bd5971687b72221736222637e03140d (patch)
treee639967a7baf1b1c6a0d1b5e0babc8083c7faad4 /fs/notify/notification.c
parent8ba8fa917093510cdcb4ec8ff8b9603e1b525658 (diff)
downloadlinux-5838d4442bd5971687b72221736222637e03140d.tar.xz
fanotify: fix double free of pending permission events
Commit 85816794240b ("fanotify: Fix use after free for permission events") introduced a double free issue for permission events which are pending in group's notification queue while group is being destroyed. These events are freed from fanotify_handle_event() but they are not removed from groups notification queue and thus they get freed again from fsnotify_flush_notify(). Fix the problem by removing permission events from notification queue before freeing them if we skip processing access response. Also expand comments in fanotify_release() to explain group shutdown in detail. Fixes: 85816794240b9659e66e4d9b0df7c6e814e5f603 Signed-off-by: Jan Kara <jack@suse.cz> Reported-by: Douglas Leeder <douglas.leeder@sophos.com> Tested-by: Douglas Leeder <douglas.leeder@sophos.com> Reported-by: Heinrich Schuchard <xypron.glpk@gmx.de> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/notify/notification.c')
-rw-r--r--fs/notify/notification.c18
1 files changed, 17 insertions, 1 deletions
diff --git a/fs/notify/notification.c b/fs/notify/notification.c
index 1d394220acbe..a95d8e037aeb 100644
--- a/fs/notify/notification.c
+++ b/fs/notify/notification.c
@@ -73,7 +73,8 @@ void fsnotify_destroy_event(struct fsnotify_group *group,
/* Overflow events are per-group and we don't want to free them */
if (!event || event->mask == FS_Q_OVERFLOW)
return;
-
+ /* If the event is still queued, we have a problem... */
+ WARN_ON(!list_empty(&event->list));
group->ops->free_event(event);
}
@@ -125,6 +126,21 @@ queue:
}
/*
+ * Remove @event from group's notification queue. It is the responsibility of
+ * the caller to destroy the event.
+ */
+void fsnotify_remove_event(struct fsnotify_group *group,
+ struct fsnotify_event *event)
+{
+ mutex_lock(&group->notification_mutex);
+ if (!list_empty(&event->list)) {
+ list_del_init(&event->list);
+ group->q_len--;
+ }
+ mutex_unlock(&group->notification_mutex);
+}
+
+/*
* Remove and return the first event from the notification list. It is the
* responsibility of the caller to destroy the obtained event
*/