Date: Fri, 1 Apr 2016 16:18:28 +0100
From: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-kernel@vger.kernel.org, linux-block@vger.kernel.org,
        Johannes Thumshirn <jthumshirn@suse.de>
Subject: Re: [PATCH v2] block: fix possible NULL dereference
Message-ID: <20160401151828.GA20149@sudip-tp>
References: <1459521258-18534-1-git-send-email-sudipm.mukherjee@gmail.com>
 <56FE87DF.3000603@kernel.dk>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <56FE87DF.3000603@kernel.dk>
User-Agent: Mutt/1.5.23 (2014-03-12)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 928
Lines: 24

On Fri, Apr 01, 2016 at 08:38:23AM -0600, Jens Axboe wrote:
> On 04/01/2016 08:34 AM, Sudip Mukherjee wrote:
> >We were checking for iter to be NULL after dereferencing it. There is
> >actually no need to check for iter to be NULL as all the callers of
> >blk_rq_map_user_iov() does call it with a valid pointer to
> >struct iov_iter.
> >But as iter->count can be NULL so the assignment to copy is being done
> >after checking for it.
> >
> >Signed-off-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
> >---
> >
> >v2: removed the check for iter
> >v1: moved the assignment to copy after check for iter and iter->count
> 
> Your subject is wrong (there's no NULL deref). Ditto for the commit message
> - it can be zero, not NULL. The latter would imply a memory address, but
> it's just an integer.

oops. I should have checked. I wanted to keep the commit message similar to
v1. I will send a v3 for this.

regards
sudip