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

Message-ID: <20160825073826.GB18622@lst.de>
Date:   Thu, 25 Aug 2016 09:38:26 +0200
From:   Christoph Hellwig <hch@....de>
To:     Andrey Ryabinin <aryabinin@...tuozzo.com>
Cc:     Jens Axboe <axboe@...com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        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 Tue, Aug 23, 2016 at 06:55:31PM +0300, 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.
> 
> Signed-off-by: Andrey Ryabinin <aryabinin@...tuozzo.com>

Looks fine,

Reviewed-by: Christoph Hellwig <hch@....de>