[PATCH stable-5.15 2/3] usb: dwc3: qcom: fix use-after-free on runtime-PM wakeup

Johan Hovold
2022-09-06T12:07:25Z

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 5.15 ]
Signed-off-by: Johan Hovold <johan+linaro@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 873bf5041117..d0352daab012 100644
--- a/drivers/usb/dwc3/dwc3-qcom.c
+++ b/drivers/usb/dwc3/dwc3-qcom.c
@@ -296,6 +296,14 @@ static void dwc3_qcom_interconnect_exit(struct dwc3_qcom *qcom)
icc_put(qcom->icc_path_apps);
}

+/* 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) {
@@ -411,7 +419,11 @@ 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 f29a264635aa..2078e9d70292 100644
--- a/drivers/usb/dwc3/host.c
+++ b/drivers/usb/dwc3/host.c
@@ -130,4 +130,5 @@ int dwc3_host_init(struct dwc3 *dwc)
void dwc3_host_exit(struct dwc3 *dwc)
{
platform_device_unregister(dwc->xhci);
+ dwc->xhci = NULL;
}
--
2.35.1