xhci: guard accesses to ep_state in xhci_endpoint_reset()

commit a01ba2a3378be85538e0183ae5367c1bc1d5aaf3 upstream.

See raspberrypi/linux#3981

Two read-modify-write cycles on ep->ep_state are not guarded by
xhci->lock. Fix these.

Fixes: f524946 ("xhci: Clear the host side toggle manually when endpoint is soft reset")
Cc: [email protected]
Signed-off-by: Jonathan Bell <[email protected]>
Signed-off-by: Mathias Nyman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

drivers/usb/host/xhci.c

@@ -3184,10 +3184,13 @@ static void xhci_endpoint_reset(struct usb_hcd *hcd,
 	ep = &vdev->eps[ep_index];
 
 	/* Bail out if toggle is already being cleared by a endpoint reset */
+	spin_lock_irqsave(&xhci->lock, flags);
 	if (ep->ep_state & EP_HARD_CLEAR_TOGGLE) {
 		ep->ep_state &= ~EP_HARD_CLEAR_TOGGLE;
+		spin_unlock_irqrestore(&xhci->lock, flags);
 		return;
 	}
+	spin_unlock_irqrestore(&xhci->lock, flags);
 	/* Only interrupt and bulk ep's use data toggle, USB2 spec 5.5.4-> */
 	if (usb_endpoint_xfer_control(&host_ep->desc) ||
 	    usb_endpoint_xfer_isoc(&host_ep->desc))
@@ -3289,8 +3292,10 @@ static void xhci_endpoint_reset(struct usb_hcd *hcd,
 	xhci_free_command(xhci, cfg_cmd);
 cleanup:
 	xhci_free_command(xhci, stop_cmd);
+	spin_lock_irqsave(&xhci->lock, flags);
 	if (ep->ep_state & EP_SOFT_CLEAR_TOGGLE)
 		ep->ep_state &= ~EP_SOFT_CLEAR_TOGGLE;
+	spin_unlock_irqrestore(&xhci->lock, flags);
 }
 
 static int xhci_check_streams_endpoint(struct xhci_hcd *xhci,