Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Subject: Re: [PATCH] selftests/resctrl: Fix null pointer dereference on open
 failed
To:     "Colin King (gmail)" <colin.i.king@gmail.com>,
        Fenghua Yu <fenghua.yu@intel.com>,
        Reinette Chatre <reinette.chatre@intel.com>,
        Shuah Khan <shuah@kernel.org>, Babu Moger <babu.moger@amd.com>,
        Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>,
        linux-kselftest@vger.kernel.org
Cc:     kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org,
        Shuah Khan <skhan@linuxfoundation.org>
References: <20220424211536.1373878-1-colin.i.king@gmail.com>
 <04a35a47-d83a-67a1-5ed4-ba314c6e1ecf@linuxfoundation.org>
 <604ea061-c566-e032-67cf-9bc622aa76ae@gmail.com>
From:   Shuah Khan <skhan@linuxfoundation.org>
Message-ID: <a238cdbb-e5fd-64f1-ea18-8ef2e7481d33@linuxfoundation.org>
Date:   Mon, 25 Apr 2022 10:21:29 -0600
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
 Thunderbird/78.8.1
MIME-Version: 1.0
In-Reply-To: <604ea061-c566-e032-67cf-9bc622aa76ae@gmail.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 4/25/22 10:06 AM, Colin King (gmail) wrote:
> On 25/04/2022 16:51, Shuah Khan wrote:
>> On 4/24/22 3:15 PM, Colin Ian King wrote:
>>> Currently if opening /dev/null fails to open then file pointer fp
>>> is null and further access to fp via fprintf will cause a null
>>> pointer dereference. Fix this by returning a negative error value
>>> when a null fp is detected.
>>>
>>
>> How did you find this problem and how can it be reproduced? Is there
>> a case where test fails to open "/dev/null"?
> 
> Found with static analysis, cppcheck. Open on /dev/null is unlikely to fail, but it's good to fail reliably rather than have a SIGSEGV :-)
> 

I don't see how /dev/null open could fail here in this test.
However, I will take this fix. Please add information how
you found it and include the cppheck log in the commit log
and send me v2.

thanks,
-- Shuah