linux-kernel - Re: [PATCH v3 06/15] arm64: dts: qcom: sc8280xp: Fix the base addresses of LLCC banks

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Date:   Wed, 21 Dec 2022 00:55:03 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc:     Steev Klimaszewski <steev@...i.org>, andersson@...nel.org,
        robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        tony.luck@...el.com, quic_saipraka@...cinc.com,
        konrad.dybcio@...aro.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, james.morse@....com,
        mchehab@...nel.org, rric@...nel.org, linux-edac@...r.kernel.org,
        quic_ppareek@...cinc.com, luca.weiss@...rphone.com,
        ahalaney@...hat.com
Subject: Re: [PATCH v3 06/15] arm64: dts: qcom: sc8280xp: Fix the base
 addresses of LLCC banks

On Tue, Dec 20, 2022 at 03:22:07PM +0530, Manivannan Sadhasivam wrote:
> This is a genuine use-after-free bug that happens because the edac core frees
> the memory assigned to "llcc_driv_data" pointer that gets passed as "pvt_info".
> 
> Here, the LLCC driver is one creating the "qcom_llcc_edac" platform device and
> also allocating memory for "llcc_driv_data". But since during qcom_edac driver
> removal, we are just unregistering the driver and the platform device still
> stays around, the edac driver is not supposed to free any memory associated
> with the platform device.

If you mean

__edac_device_free_ctl_info()

it is very well supposed to free it as it allocates it in
edac_device_alloc_ctl_info().

If qcom_llcc_edac_probe() simply goes and assigns something of its own
to edev_ctl->pvt_info, then that driver gets to keep the pieces ofc.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette