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authorOleksij Rempel <linux@rempel-privat.de>2013-07-21 15:36:19 +0200
committerSarah Sharp <sarah.a.sharp@linux.intel.com>2013-07-25 08:10:09 -0700
commitd66eaf9f89502971fddcb0de550b01fa6f409d83 (patch)
treef8f938260a47de6d06ccb6858618708c3c312aed /drivers/usb
parent07f3cb7c28bf3f4dd80bfb136cf45810c46ac474 (diff)
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 e9df17eb1408cfafa3d1844bfc7f22c7237b31b8 "USB: xhci: Correct assumptions about number of rings per endpoint" Signed-off-by: Oleksij Rempel <linux@rempel-privat.de> Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com> Cc: stable@vger.kernel.org
Diffstat (limited to 'drivers/usb')
-rw-r--r--drivers/usb/host/xhci-ring.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 1e57eafa6910..5b08cd85f8e7 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -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 */
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);
return;
}