Message-ID: <80339c7f-1cea-3c97-7dc4-5efb4597cb69@linaro.org>
Date:   Wed, 22 Feb 2023 15:50:30 +0100
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101
 Thunderbird/102.8.0
Subject: Re: [PATCH 2/2] soundwire: qcom: gracefully handle too many ports in
 DT
Content-Language: en-US
To:     Konrad Dybcio <konrad.dybcio@linaro.org>,
        Andy Gross <agross@kernel.org>,
        Bjorn Andersson <andersson@kernel.org>,
        Vinod Koul <vkoul@kernel.org>,
        Bard Liao <yung-chuan.liao@linux.intel.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>,
        Sanyog Kale <sanyog.r.kale@intel.com>,
        linux-arm-msm@vger.kernel.org, alsa-devel@alsa-project.org,
        linux-kernel@vger.kernel.org
References: <20230222144412.237832-1-krzysztof.kozlowski@linaro.org>
 <20230222144412.237832-2-krzysztof.kozlowski@linaro.org>
 <dc544641-b9f1-96b4-95a1-30fafc0712e5@linaro.org>
From:   Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
In-Reply-To: <dc544641-b9f1-96b4-95a1-30fafc0712e5@linaro.org>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 22/02/2023 15:47, Konrad Dybcio wrote:
> 
> 
> On 22.02.2023 15:44, Krzysztof Kozlowski wrote:
>> There are two issues related to the number of ports coming from
>> Devicetree when exceeding in total QCOM_SDW_MAX_PORTS.  Both lead to
>> incorrect memory accesses:
>> 1. With DTS having too big value of input or output ports, the driver,
>>    when copying port parameters from local/stack arrays into 'pconfig'
>>    array in 'struct qcom_swrm_ctrl', will iterate over their sizes.
>>
>> 2. If DTS also has too many parameters for these ports (e.g.
>>    qcom,ports-sinterval-low), the driver will overflow buffers on the
>>    stack when reading these properties from DTS.
>>
>> Add a sanity check so incorrect DTS will not cause kernel memory
>> corruption.
>>
>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
>> ---
> Fixes: 02efb49aa805 ("soundwire: qcom: add support for SoundWire controller")

Can be... but is it really a bug of the kernel? Issue is visible with
incorrect DTS and it's not the kernel's job to fix it. If DTS has
incorrect values (e.g. IO addresses) system won't work anyway and that's
the same type of bug.

Best regards,
Krzysztof