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Commit 8fb33166 authored by Jan Kara's avatar Jan Kara Committed by Greg Kroah-Hartman
Browse files

inotify: Avoid reporting event with invalid wd 



commit c915d8f5918bea7c3962b09b8884ca128bfd9b0c upstream.

When inotify_freeing_mark() races with inotify_handle_inode_event() it
can happen that inotify_handle_inode_event() sees that i_mark->wd got
already reset to -1 and reports this value to userspace which can
confuse the inotify listener. Avoid the problem by validating that wd is
sensible (and pretend the mark got removed before the event got
generated otherwise).

CC: stable@vger.kernel.org
Fixes: 7e790dd5 ("inotify: fix error paths in inotify_update_watch")
Message-Id: <20230424163219.9250-1-jack@suse.cz>
Reported-by: default avatar <syzbot+4a06d4373fd52f0b2f9c@syzkaller.appspotmail.com>
Reviewed-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 0ccea97a

fs/notify/inotify/inotify_fsnotify.c

+9 −2
Original line number Diff line number Diff line
@@ -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)))
@@ -90,6 +90,13 @@ int inotify_handle_event(struct fsnotify_group *group, 
	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
@@ -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)