audit: Fix use after free in audit_remove_watch_rule()
authorJan Kara <jack@suse.cz>
Tue, 15 Aug 2017 11:00:36 +0000 (13:00 +0200)
committerPaul Moore <paul@paul-moore.com>
Tue, 15 Aug 2017 19:58:17 +0000 (15:58 -0400)
commitd76036ab47eafa6ce52b69482e91ca3ba337d6d6
tree36e9cad8d69f7b801ef976a4f86a5276e7c59fe5
parentb0659ae5e30074ede1dc08f2c6d64f0c11d64e0f
audit: Fix use after free in audit_remove_watch_rule()

audit_remove_watch_rule() drops watch's reference to parent but then
continues to work with it. That is not safe as parent can get freed once
we drop our reference. The following is a trivial reproducer:

mount -o loop image /mnt
touch /mnt/file
auditctl -w /mnt/file -p wax
umount /mnt
auditctl -D
<crash in fsnotify_destroy_mark()>

Grab our own reference in audit_remove_watch_rule() earlier to make sure
mark does not get freed under us.

CC: stable@vger.kernel.org
Reported-by: Tony Jones <tonyj@suse.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Tested-by: Tony Jones <tonyj@suse.de>
Signed-off-by: Paul Moore <paul@paul-moore.com>
kernel/audit_watch.c