Commit d3bc0fa8 authored Aug 20, 2018 by Jan Kara

fsnotify: fix false positive warning on inode delete



When inode is getting deleted and someone else holds reference to a mark
attached to the inode, we just detach the connector from the inode. In
that case fsnotify_put_mark() called from fsnotify_destroy_marks() will
decide to recalculate mask for the inode and __fsnotify_recalc_mask()
will WARN about invalid connector type:

WARNING: CPU: 1 PID: 12015 at fs/notify/mark.c:139
__fsnotify_recalc_mask+0x2d7/0x350 fs/notify/mark.c:139

Actually there's no reason to warn about detached connector in
__fsnotify_recalc_mask() so just silently skip updating the mask in such
case.

Reported-by:  <syzbot+c34692a51b9a6ca93540@syzkaller.appspotmail.com>
Fixes: 3ac70bfc ("fsnotify: add helper to get mask from connector")
Signed-off-by: Jan Kara <jack@suse.cz>

parent 2ad0d526

fs/notify/mark.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -132,13 +132,13 @@ static void __fsnotify_recalc_mask(struct fsnotify_mark_connector *conn)
		struct fsnotify_mark *mark;

		assert_spin_locked(&conn->lock);
		/* We can get detached connector here when inode is getting unlinked. */
		if (!fsnotify_valid_obj_type(conn->type))
		return;
		hlist_for_each_entry(mark, &conn->list, obj_list) {
		if (mark->flags & FSNOTIFY_MARK_FLAG_ATTACHED)
		new_mask \|= mark->mask;
		}
		if (WARN_ON(!fsnotify_valid_obj_type(conn->type)))
		return;

		*fsnotify_conn_mask_p(conn) = new_mask;
		}

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