3 files changed, 22 insertions, 3 deletions

diff --git a/fs/notify/inotify/inotify.h b/fs/notify/inotify/inotify.h
index 3f246f7b8a92..8b8bf52dd08b 100644
--- a/fs/notify/inotify/inotify.h
+++ b/fs/notify/inotify/inotify.h
@@ -22,6 +22,18 @@ static inline struct inotify_event_info *INOTIFY_E(struct fsnotify_event *fse)
 	return container_of(fse, struct inotify_event_info, fse);
 }
 
+/*
+ * INOTIFY_USER_FLAGS represents all of the mask bits that we expose to
+ * userspace.  There is at least one bit (FS_EVENT_ON_CHILD) which is
+ * used only internally to the kernel.
+ */
+#define INOTIFY_USER_MASK (IN_ALL_EVENTS | IN_ONESHOT | IN_EXCL_UNLINK)
+
+static inline __u32 inotify_mark_user_mask(struct fsnotify_mark *fsn_mark)
+{
+	return fsn_mark->mask & INOTIFY_USER_MASK;
+}
+
 extern void inotify_ignored_and_remove_idr(struct fsnotify_mark *fsn_mark,
 					   struct fsnotify_group *group);
 extern int inotify_handle_event(struct fsnotify_group *group,
diff --git a/fs/notify/inotify/inotify_fsnotify.c b/fs/notify/inotify/inotify_fsnotify.c
index 589dee962993..a3cbfd38f1f6 100644
--- a/fs/notify/inotify/inotify_fsnotify.c
+++ b/fs/notify/inotify/inotify_fsnotify.c
@@ -66,7 +66,7 @@ int inotify_handle_event(struct fsnotify_group *group,
 	struct inotify_event_info *event;
 	struct fsnotify_event *fsn_event;
 	int ret;
-	int len = 0;
+	int len = 0, wd;
 	int alloc_len = sizeof(struct inotify_event_info);
 
 	if (WARN_ON(fsnotify_iter_vfsmount_mark(iter_info)))
@@ -91,6 +91,13 @@ int inotify_handle_event(struct fsnotify_group *group,
 			      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
 	 * security repercussion.
@@ -120,7 +127,7 @@ int inotify_handle_event(struct fsnotify_group *group,
 	fsn_event = &event->fse;
 	fsnotify_init_event(fsn_event, (unsigned long)inode);
 	event->mask = mask;
-	event->wd = i_mark->wd;
+	event->wd = wd;
 	event->sync_cookie = cookie;
 	event->name_len = len;
 	if (len)
diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
index 81ffc8629fc4..b949b2c02f4b 100644
--- a/fs/notify/inotify/inotify_user.c
+++ b/fs/notify/inotify/inotify_user.c
@@ -86,7 +86,7 @@ static inline __u32 inotify_arg_to_mask(u32 arg)
 	mask = (FS_IN_IGNORED | FS_EVENT_ON_CHILD | FS_UNMOUNT);
 
 	/* mask off the flags used to open the fd */
-	mask |= (arg & (IN_ALL_EVENTS | IN_ONESHOT | IN_EXCL_UNLINK));
+	mask |= (arg & INOTIFY_USER_MASK);
 
 	return mask;
 }