In current scenario if Plug-out and Plug-In performed continuously there could be a chance while checking for dwc->gadget_driver in dwc3_gadget_suspend, a NULL pointer dereference may occur.
Call Stack:
CPU1: CPU2: gadget_unbind_driver dwc3_suspend_common dwc3_gadget_stop dwc3_gadget_suspend dwc3_disconnect_gadget
CPU1 basically clears the variable and CPU2 checks the variable. Consider CPU1 is running and right before gadget_driver is cleared and in parallel CPU2 executes dwc3_gadget_suspend where it finds dwc->gadget_driver which is not NULL and resumes execution and then CPU1 completes execution. CPU2 executes dwc3_disconnect_gadget where it checks dwc->gadget_driver is already NULL because of which the NULL pointer deference occur.
Cc: stable@vger.kernel.org Fixes: 9772b47a4c29 ("usb: dwc3: gadget: Fix suspend/resume during device mode") Acked-by: Thinh Nguyen Thinh.Nguyen@synopsys.com Signed-off-by: Uttkarsh Aggarwal quic_uaggarwa@quicinc.com ---
changes in v3: Corrected fixes tag and typo mistake in commit message dw3_gadget_stop -> dwc3_gadget_stop.
Link to v2: https://lore.kernel.org/linux-usb/CAKzKK0r8RUqgXy1o5dndU21KuTKtyZ5rn5Fb9sZqT...
Changes in v2: Added cc and fixes tag missing in v1.
Link to v1: https://lore.kernel.org/linux-usb/20240110095532.4776-1-quic_uaggarwa@quicin...
drivers/usb/dwc3/gadget.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c index 019368f8e9c4..564976b3e2b9 100644 --- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -4709,15 +4709,13 @@ int dwc3_gadget_suspend(struct dwc3 *dwc) unsigned long flags; int ret;
- if (!dwc->gadget_driver) - return 0; - ret = dwc3_gadget_soft_disconnect(dwc); if (ret) goto err;
spin_lock_irqsave(&dwc->lock, flags); - dwc3_disconnect_gadget(dwc); + if (dwc->gadget_driver) + dwc3_disconnect_gadget(dwc); spin_unlock_irqrestore(&dwc->lock, flags);
return 0;