Commit d66eaf9f authored by Oleksij Rempel's avatar Oleksij Rempel Committed by Sarah Sharp

xhci: fix null pointer dereference on ring_doorbell_for_active_rings

in some cases where device is attched to xhci port and do not responding,
for example ath9k_htc with stalled firmware, kernel will
crash on ring_doorbell_for_active_rings.
This patch check if pointer exist before it is used.

This patch should be backported to kernels as old as 2.6.35, that
contain the commit e9df17eb "USB: xhci:
Correct assumptions about number of rings per endpoint"
Signed-off-by: default avatarOleksij Rempel <linux@rempel-privat.de>
Signed-off-by: default avatarSarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable@vger.kernel.org
parent 07f3cb7c
...@@ -434,7 +434,7 @@ static void ring_doorbell_for_active_rings(struct xhci_hcd *xhci, ...@@ -434,7 +434,7 @@ static void ring_doorbell_for_active_rings(struct xhci_hcd *xhci,
/* A ring has pending URBs if its TD list is not empty */ /* A ring has pending URBs if its TD list is not empty */
if (!(ep->ep_state & EP_HAS_STREAMS)) { if (!(ep->ep_state & EP_HAS_STREAMS)) {
if (!(list_empty(&ep->ring->td_list))) if (ep->ring && !(list_empty(&ep->ring->td_list)))
xhci_ring_ep_doorbell(xhci, slot_id, ep_index, 0); xhci_ring_ep_doorbell(xhci, slot_id, ep_index, 0);
return; return;
} }
......
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