[PATCH 6.1 053/197] usb: dwc3: gadget: Fix NULL pointer dereference in dwc3_gadget_suspend

Greg Kroah-Hartman
2024-02-20T21:00:38Z

From: Uttkarsh Aggarwal <quic_uaggarwa@quicinc.com>

commit 61a348857e869432e6a920ad8ea9132e8d44c316 upstream.

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>
Link: https://lore.kernel.org/r/20240119094825.26530-1-quic_uaggarwa@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/usb/dwc3/gadget.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)

--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -4583,15 +4583,13 @@ 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;