linux-kernel - Re: [PATCH] fs/block_dev: fix potential NULL ptr deref in freeze

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:   Thu, 25 Aug 2016 08:39:22 -0600
From:   Jens Axboe <axboe@...com>
To:     Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Viro <viro@...iv.linux.org.uk>
CC:     <linux-fsdevel@...r.kernel.org>,
        Maxim Patlasov <mpatlasov@...tuozzo.com>,
        Christoph Hellwig <hch@....de>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] fs/block_dev: fix potential NULL ptr deref in
 freeze_bdev()

On 08/23/2016 09:55 AM, Andrey Ryabinin wrote:
> Calling freeze_bdev() twice on the same block device without mounted
> filesystem get_super() will return NULL, which will lead to NULL-ptr
> dereference later in drop_super().
>
> Check get_super() result to fix that.
>
> Note, that this is a purely theoretical issue. We have only 3
> freeze_bdev() callers. 2 of them are in filesystem code and used on a
> device with mounted fs. The third one in lock_fs() has protection in
> upper-layer code against freezing block device the second time without
> thawing it first.

Applied, thanks.

-- 
Jens Axboe