Merge tag 'fsnotify_for_v6.4-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs

Pull inotify fix from Jan Kara:
 "A fix for possibly reporting invalid watch descriptor with inotify
  event"

* tag 'fsnotify_for_v6.4-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  inotify: Avoid reporting event with invalid wd

Author: torvalds

fs/notify/inotify/inotify_fsnotify.c

@@ -65,7 +65,7 @@ int inotify_handle_inode_event(struct fsnotify_mark *inode_mark, u32 mask,
 	struct fsnotify_event *fsn_event;
 	struct fsnotify_group *group = inode_mark->group;
 	int ret;
-	int len = 0;
+	int len = 0, wd;
 	int alloc_len = sizeof(struct inotify_event_info);
 	struct mem_cgroup *old_memcg;
 
@@ -80,6 +80,13 @@ int inotify_handle_inode_event(struct fsnotify_mark *inode_mark, u32 mask,
 	i_mark = container_of(inode_mark, struct inotify_inode_mark,
 			      fsn_mark);
 
+	/*
+	 * We can be racing with mark being detached. Don't report event with
+	 * invalid wd.
+	 */
+	wd = READ_ONCE(i_mark->wd);
+	if (wd == -1)
+		return 0;
 	/*
 	 * Whoever is interested in the event, pays for the allocation. Do not
 	 * trigger OOM killer in the target monitoring memcg as it may have
@@ -110,7 +117,7 @@ int inotify_handle_inode_event(struct fsnotify_mark *inode_mark, u32 mask,
 	fsn_event = &event->fse;
 	fsnotify_init_event(fsn_event);
 	event->mask = mask;
-	event->wd = i_mark->wd;
+	event->wd = wd;
 	event->sync_cookie = cookie;
 	event->name_len = len;
 	if (len)