diff options
| author | Jan Kara <jack@suse.cz> | 2017-08-15 13:00:36 +0200 |
|---|---|---|
| committer | Sasha Levin <alexander.levin@verizon.com> | 2017-10-03 21:36:29 -0400 |
| commit | 0387edf8f71505cb837aa4dbde0b73a3ee658246 (patch) | |
| tree | a450ff949f8da949d2e065892bd959483f116407 /kernel | |
| parent | 33e8fdfba09e5a5d2e419c509ffb93d03dffe754 (diff) | |
audit: Fix use after free in audit_remove_watch_rule()
[ Upstream commit d76036ab47eafa6ce52b69482e91ca3ba337d6d6 ]
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>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Diffstat (limited to 'kernel')
| -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 6e30024d9aac..d53c6e284e87 100644 --- a/kernel/audit_watch.c +++ b/kernel/audit_watch.c @@ -455,13 +455,15 @@ 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); } } |