From: Johan Hovold johan+linaro@kernel.org
commit a872ab303d5ddd4c965f9cd868677781a33ce35a upstream.
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 Reviewed-by: Matthias Kaehlcke mka@chromium.org Reviewed-by: Manivannan Sadhasivam manivannan.sadhasivam@linaro.org Signed-off-by: Johan Hovold johan+linaro@kernel.org Link: https://lore.kernel.org/r/20220804151001.23612-5-johan+linaro@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org [ johan: adjust context for 5.4 ] Signed-off-by: Johan Hovold johan+linaro@kernel.org Signed-off-by: Johan Hovold johan@kernel.org --- drivers/usb/dwc3/dwc3-qcom.c | 14 +++++++++++++- drivers/usb/dwc3/host.c | 1 + 2 files changed, 14 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c index 5bb5384f3612..9d5320562e81 100644 --- a/drivers/usb/dwc3/dwc3-qcom.c +++ b/drivers/usb/dwc3/dwc3-qcom.c @@ -173,6 +173,14 @@ static int dwc3_qcom_register_extcon(struct dwc3_qcom *qcom) return 0; }
+/* Only usable in contexts where the role can not change. */ +static bool dwc3_qcom_is_host(struct dwc3_qcom *qcom) +{ + struct dwc3 *dwc = platform_get_drvdata(qcom->dwc3); + + return dwc->xhci; +} + static void dwc3_qcom_disable_interrupts(struct dwc3_qcom *qcom) { if (qcom->hs_phy_irq) { @@ -280,7 +288,11 @@ static irqreturn_t qcom_dwc3_resume_irq(int irq, void *data) if (qcom->pm_suspended) return IRQ_HANDLED;
- if (dwc->xhci) + /* + * This is safe as role switching is done from a freezable workqueue + * and the wakeup interrupts are disabled as part of resume. + */ + if (dwc3_qcom_is_host(qcom)) pm_runtime_resume(&dwc->xhci->dev);
return IRQ_HANDLED; diff --git a/drivers/usb/dwc3/host.c b/drivers/usb/dwc3/host.c index 1a3878a3be78..124e9f80dccd 100644 --- a/drivers/usb/dwc3/host.c +++ b/drivers/usb/dwc3/host.c @@ -142,4 +142,5 @@ void dwc3_host_exit(struct dwc3 *dwc) phy_remove_lookup(dwc->usb3_generic_phy, "usb3-phy", dev_name(dwc->dev)); platform_device_unregister(dwc->xhci); + dwc->xhci = NULL; }