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fsnotify: Do not return merged event from fsnotify_add_notify_event()

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The event returned from fsnotify_add_notify_event() cannot ever be used
safely as the event may be freed by the time the function returns (after
dropping notification_mutex). So change the prototype to just return
whether the event was added or merged into some existing event.

Reported-and-tested-by: Jiri Kosina <jkosina@suse.cz>
Reported-and-tested-by: Dave Jones <davej@fedoraproject.org>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Jan Kara
2014-01-28 18:53:22 +01:00
parent 13116dfd13
commit 83c0e1b442
4 changed files with 30 additions and 39 deletions
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18
fs/notify/fanotify/fanotify.c
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@@ -28,8 +28,7 @@ static bool should_merge(struct fsnotify_event *old_fsn,
}
/* and the list better be locked by something too! */
static struct fsnotify_event *fanotify_merge(struct list_head *list,
struct fsnotify_event *event)
static int fanotify_merge(struct list_head *list, struct fsnotify_event *event)
{
struct fsnotify_event *test_event;
bool do_merge = false;
@@ -43,7 +42,7 @@ static struct fsnotify_event *fanotify_merge(struct list_head *list,
* one we should check for permission response.
*/
if (event->mask & FAN_ALL_PERM_EVENTS)
return NULL;
return 0;
#endif
list_for_each_entry_reverse(test_event, list, list) {
@@ -54,10 +53,10 @@ static struct fsnotify_event *fanotify_merge(struct list_head *list,
}
if (!do_merge)
return NULL;
return 0;
test_event->mask |= event->mask;
return test_event;
return 1;
}
#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
@@ -153,7 +152,6 @@ static int fanotify_handle_event(struct fsnotify_group *group,
int ret = 0;
struct fanotify_event_info *event;
struct fsnotify_event *fsn_event;
struct fsnotify_event *notify_fsn_event;
BUILD_BUG_ON(FAN_ACCESS != FS_ACCESS);
BUILD_BUG_ON(FAN_MODIFY != FS_MODIFY);
@@ -192,13 +190,11 @@ static int fanotify_handle_event(struct fsnotify_group *group,
event->response = 0;
#endif
notify_fsn_event = fsnotify_add_notify_event(group, fsn_event,
fanotify_merge);
if (notify_fsn_event) {
ret = fsnotify_add_notify_event(group, fsn_event, fanotify_merge);
if (ret) {
/* Our event wasn't used in the end. Free it. */
fsnotify_destroy_event(group, fsn_event);
if (IS_ERR(notify_fsn_event))
return PTR_ERR(notify_fsn_event);
ret = 0;
}
#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS