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| author | Jan Kara <jack@suse.cz> | 2017-08-15 13:00:36 +0200 |
|---|---|---|
| committer | Paul Moore <paul@paul-moore.com> | 2017-08-15 15:58:17 -0400 |
| commit | d76036ab47eafa6ce52b69482e91ca3ba337d6d6 (patch) | |
| tree | 36e9cad8d69f7b801ef976a4f86a5276e7c59fe5 /kernel/audit_watch.c | |
| parent | b0659ae5e30074ede1dc08f2c6d64f0c11d64e0f (diff) | |
| download | linux-d76036ab47eafa6ce52b69482e91ca3ba337d6d6.tar.gz | |
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>
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 e0656bd63036..1c7ded42f82f 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); } } |