From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754591AbeD3P0a (ORCPT ); Mon, 30 Apr 2018 11:26:30 -0400 Received: from gateway23.websitewelcome.com ([192.185.50.129]:31172 "EHLO gateway23.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752939AbeD3P02 (ORCPT ); Mon, 30 Apr 2018 11:26:28 -0400 X-Authority-Reason: nr=8 Subject: Re: [PATCH][next] media: ispstat: don't dereference user_cfg before a null check To: Sakari Ailus , Laurent Pinchart Cc: Colin King , Mauro Carvalho Chehab , linux-media@vger.kernel.org, kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org References: <20180424130618.18211-1-colin.king@canonical.com> <20180426083731.72bmygsp2waf3eeu@valkosipuli.retiisi.org.uk> <2302951.d1m0yxIoYN@avalon> <20180430151503.d3kq2zomil6uh2xf@valkosipuli.retiisi.org.uk> From: "Gustavo A. R. Silva" Message-ID: <9c1e7c1e-c391-4b91-7836-61a8b9d5489a@embeddedor.com> Date: Mon, 30 Apr 2018 10:26:25 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <20180430151503.d3kq2zomil6uh2xf@valkosipuli.retiisi.org.uk> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - gator4166.hostgator.com X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - embeddedor.com X-BWhitelist: no X-Source-IP: 187.172.56.86 X-Source-L: No X-Exim-ID: 1fDAh9-003xkh-6j X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: ([192.168.1.74]) [187.172.56.86]:59962 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 7 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Gustavo A. R. Silva" Date: Mon, 30 Apr 2018 15:26:25 +0000 Subject: Re: [PATCH][next] media: ispstat: don't dereference user_cfg before a null check Message-Id: <9c1e7c1e-c391-4b91-7836-61a8b9d5489a@embeddedor.com> List-Id: References: <20180424130618.18211-1-colin.king@canonical.com> <20180426083731.72bmygsp2waf3eeu@valkosipuli.retiisi.org.uk> <2302951.d1m0yxIoYN@avalon> <20180430151503.d3kq2zomil6uh2xf@valkosipuli.retiisi.org.uk> In-Reply-To: <20180430151503.d3kq2zomil6uh2xf@valkosipuli.retiisi.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Sakari Ailus , Laurent Pinchart Cc: Colin King , Mauro Carvalho Chehab , linux-media@vger.kernel.org, kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org 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