diff options
| author | Jan Kara <jack@suse.cz> | 2017-08-15 13:00:36 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-08-24 17:12:18 -0700 |
| commit | adcfbb2d9e386517db84ac56fa3e4abd56db75b3 (patch) | |
| tree | ccf3b14ac7b174821a9a21199fbf401d936bd7a0 /kernel/audit_watch.c | |
| parent | 5170d210efe44e947abecd60fd0805e970add4fc (diff) | |
audit: Fix use after free in audit_remove_watch_rule()
commit d76036ab47eafa6ce52b69482e91ca3ba337d6d6 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: 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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel/audit_watch.c')
| -rw-r--r-- | kernel/audit_watch.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/kernel/audit_watch.c b/kernel/audit_watch.c index 0d302a87f21b..690e1e3c59f7 100644 --- a/kernel/audit_watch.c +++ b/kernel/audit_watch.c @@ -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); } } |