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authorOleksij Rempel <linux@rempel-privat.de>2013-07-21 15:36:19 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-08-04 16:50:46 +0800
commit10a1c13241f682cdc866f2aa8a0e5c5373470ecb (patch)
tree756374b512fc14b315e30fac4416f52036673904
parenta875d82eda58712d81caf78ebb515fb072187138 (diff)
downloadlinux-linaro-stable-10a1c13241f682cdc866f2aa8a0e5c5373470ecb.tar.gz
xhci: fix null pointer dereference on ring_doorbell_for_active_rings
commit d66eaf9f89502971fddcb0de550b01fa6f409d83 upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-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 1969c001b3f9..cc3bfc5d590d 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;
}