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@xxxxxxxxxxxxxxx>
Fixes: 9772b47a4c29 ("usb: dwc3: gadget: Fix suspend/resume during device mode")
Acked-by: Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx>
Signed-off-by: Uttkarsh Aggarwal <quic_uaggarwa@xxxxxxxxxxx>
---
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/CAKzKK0r8RUqgXy1o5dndU21KuTKtyZ5rn5Fb9sZqTPZqAjT_9A@xxxxxxxxxxxxxx/T/#t
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@xxxxxxxxxxx/T/#u
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;
--
2.17.1
