Commit dfaf892d authored by Jan Kara's avatar Jan Kara Committed by Greg Kroah-Hartman

audit: Fix use after free in audit_remove_watch_rule()

commit d76036ab upstream.

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.
Reported-by: default avatarTony Jones <tonyj@suse.de>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
Tested-by: default avatarTony Jones <tonyj@suse.de>
Signed-off-by: default avatarPaul Moore <paul@paul-moore.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent a0fb6543
......@@ -457,13 +457,15 @@ void audit_remove_watch_rule(struct audit_krule *krule)
list_del(&krule->rlist);
if (list_empty(&watch->rules)) {
/*
* audit_remove_watch() drops our reference to 'parent' which
* can get freed. Grab our own reference to be safe.
*/
audit_get_parent(parent);
audit_remove_watch(watch);
if (list_empty(&parent->watches)) {
audit_get_parent(parent);
if (list_empty(&parent->watches))
fsnotify_destroy_mark(&parent->mark, audit_watch_group);
audit_put_parent(parent);
}
audit_put_parent(parent);
}
}
......
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