notify: unused event private race
inotify decides if private data it passed to get added to an event was
used by checking list_empty(). But it's possible that the event may
have been dequeued and the private event removed so it would look empty.
The fix is to use the return code from fsnotify_add_notify_event rather
than looking at the list.
Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/notify/inotify/inotify_fsnotify.c b/fs/notify/inotify/inotify_fsnotify.c
index 47cd258..5dcbafe 100644
--- a/fs/notify/inotify/inotify_fsnotify.c
+++ b/fs/notify/inotify/inotify_fsnotify.c
@@ -62,13 +62,14 @@
event_priv->wd = wd;
ret = fsnotify_add_notify_event(group, event, fsn_event_priv);
- /* EEXIST is not an error */
- if (ret == -EEXIST)
- ret = 0;
-
- /* did event_priv get attached? */
- if (list_empty(&fsn_event_priv->event_list))
+ if (ret) {
inotify_free_event_priv(fsn_event_priv);
+ /* EEXIST says we tail matched, EOVERFLOW isn't something
+ * to report up the stack. */
+ if ((ret == -EEXIST) ||
+ (ret == -EOVERFLOW))
+ ret = 0;
+ }
/*
* If we hold the entry until after the event is on the queue
diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
index f30d9bb..c172a7a 100644
--- a/fs/notify/inotify/inotify_user.c
+++ b/fs/notify/inotify/inotify_user.c
@@ -386,6 +386,7 @@
struct fsnotify_event *ignored_event;
struct inotify_event_private_data *event_priv;
struct fsnotify_event_private_data *fsn_event_priv;
+ int ret;
ignored_event = fsnotify_create_event(NULL, FS_IN_IGNORED, NULL,
FSNOTIFY_EVENT_NONE, NULL, 0,
@@ -404,10 +405,8 @@
fsn_event_priv->group = group;
event_priv->wd = ientry->wd;
- fsnotify_add_notify_event(group, ignored_event, fsn_event_priv);
-
- /* did the private data get added? */
- if (list_empty(&fsn_event_priv->event_list))
+ ret = fsnotify_add_notify_event(group, ignored_event, fsn_event_priv);
+ if (ret)
inotify_free_event_priv(fsn_event_priv);
skip_send_ignore:
diff --git a/fs/notify/notification.c b/fs/notify/notification.c
index 5213685..74b3cf3 100644
--- a/fs/notify/notification.c
+++ b/fs/notify/notification.c
@@ -171,9 +171,7 @@
struct list_head *list = &group->notification_list;
struct fsnotify_event_holder *last_holder;
struct fsnotify_event *last_event;
-
- /* easy to tell if priv was attached to the event */
- INIT_LIST_HEAD(&priv->event_list);
+ int ret = 0;
/*
* There is one fsnotify_event_holder embedded inside each fsnotify_event.
@@ -194,6 +192,7 @@
if (group->q_len >= group->max_events) {
event = &q_overflow_event;
+ ret = -EOVERFLOW;
/* sorry, no private data on the overflow event */
priv = NULL;
}
@@ -235,7 +234,7 @@
mutex_unlock(&group->notification_mutex);
wake_up(&group->notification_waitq);
- return 0;
+ return ret;
}
/*