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Date:   Thu, 4 Aug 2022 08:53:50 -0700
From:   Matthias Kaehlcke <mka@chromium.org>
To:     Johan Hovold <johan+linaro@kernel.org>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Felipe Balbi <balbi@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Andy Gross <agross@kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
        Konrad Dybcio <konrad.dybcio@somainline.org>,
        Krishna Kurapati <quic_kriskura@quicinc.com>,
        Stephen Boyd <swboyd@chromium.org>,
        Doug Anderson <dianders@chromium.org>,
        Pavankumar Kondeti <quic_pkondeti@quicinc.com>,
        quic_ppratap@quicinc.com, quic_vpulyala@quicinc.com,
        linux-arm-msm@vger.kernel.org, linux-usb@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        stable@vger.kernel.org
Subject: Re: [PATCH v2 4/9] usb: dwc3: qcom: fix use-after-free on runtime-PM
 wakeup
Message-ID: <YuvrjqSz8XGlm04l@google.com>
References: <20220804151001.23612-1-johan+linaro@kernel.org>
 <20220804151001.23612-5-johan+linaro@kernel.org>
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On Thu, Aug 04, 2022 at 05:09:56PM +0200, Johan Hovold wrote:
> The Qualcomm dwc3 runtime-PM implementation checks the xhci
> platform-device pointer in the wakeup-interrupt handler to determine
> whether the controller is in host mode and if so triggers a resume.
> 
> After a role switch in OTG mode the xhci platform-device would have been
> freed and the next wakeup from runtime suspend would access the freed
> memory.
> 
> Note that role switching is executed from a freezable workqueue, which
> guarantees that the pointer is stable during suspend.
> 
> Also note that runtime PM has been broken since commit 2664deb09306
> ("usb: dwc3: qcom: Honor wakeup enabled/disabled state"), which
> incidentally also prevents this issue from being triggered.
> 
> Fixes: a4333c3a6ba9 ("usb: dwc3: Add Qualcomm DWC3 glue driver")
> Cc: stable@vger.kernel.org      # 4.18
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>

Reviewed-by: Matthias Kaehlcke <mka@chromium.org>