xhci: Fix race between ep halt and URB cancellation

commit 526867c3ca0caa2e3e846cb993b0f961c33c2abb upstream.

The halted state of a endpoint cannot be cleared over CLEAR_HALT from a
user process, because the stopped_td variable was overwritten in the
handle_stopped_endpoint() function. So the xhci_endpoint_reset() function will
refuse the reset and communication with device can not run over this endpoint.
https://bugzilla.kernel.org/show_bug.cgi?id=60699

Signed-off-by: Florian Wolter <wolly84@web.de>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: Jonghwan Choi <jhbird.choi@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 6 insertions, 2 deletions

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 21f1f13ea262..bcfb08e41eb6 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -857,8 +857,12 @@ remove_finished_td:
                 /* Otherwise ring the doorbell(s) to restart queued transfers */
                 ring_doorbell_for_active_rings(xhci, slot_id, ep_index);
         }
-        ep->stopped_td = NULL;
-        ep->stopped_trb = NULL;
+
+        /* Clear stopped_td and stopped_trb if endpoint is not halted */
+        if (!(ep->ep_state & EP_HALTED)) {
+                ep->stopped_td = NULL;
+                ep->stopped_trb = NULL;
+        }
 
         /*
          * Drop the lock and complete the URBs in the cancelled TD list.