linux-kernel - Re: [PATCH][next] media: ispstat: don't dereference user

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Message-ID: <9c1e7c1e-c391-4b91-7836-61a8b9d5489a@embeddedor.com>
Date:   Mon, 30 Apr 2018 10:26:25 -0500
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Sakari Ailus <sakari.ailus@....fi>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     Colin King <colin.king@...onical.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, kernel-janitors@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH][next] media: ispstat: don't dereference user_cfg before a
 null check

Hi Sakari,

On 04/30/2018 10:15 AM, Sakari Ailus wrote:
>> Isn't there a guarantee that new_buf won't be NULL ? The new_buf pointer comes
>> from the parg variable in video_usercopy(), which should always point to a
>> valid buffer given that the ioctl number specifies a non-zero size.
> 
> Fair question. After looking at the code, I agree with you; there should be
> no reason to perform the check in the first place. It may have been that
> the function has been used differently in the past but the check should be
> rather removed now.
> 
> I'll drop the patch.
> 

Please, if the check isn't needed anymore, make sure it is removed.

This helps to reduce the number of false positives reported by static 
analyzers.

Thanks
--
Gustavo