linux-kernel - Re: [PATCH 2/2] soundwire: qcom: gracefully handle too many ports in DT

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Message-ID: <64c80ca9-2317-8225-2345-146e41f3c251@linaro.org>
Date:   Wed, 22 Feb 2023 15:53:29 +0100
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Vinod Koul <vkoul@...nel.org>,
        Bard Liao <yung-chuan.liao@...ux.intel.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        Sanyog Kale <sanyog.r.kale@...el.com>,
        linux-arm-msm@...r.kernel.org, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] soundwire: qcom: gracefully handle too many ports in
 DT



On 22.02.2023 15:50, Krzysztof Kozlowski wrote:
> 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@...aro.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.
I'm not sure to what extent the kernel should be responsible for
checking DT sanity, but in case of a buffer overflow, I really
think it definitely deserves a fixes tag.

Konrad

> 
> Best regards,
> Krzysztof
>