4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
commit 4b895868bb2da60a386a17cde3bf9ecbc70c79f4 upstream.
This off by one in stream_id indexing caused NULL pointer dereference and
soft lockup on machines with USB attached SCSI devices connected to a
hotpluggable xhci controller.
The code that cleans up pending URBs for dead hosts tried to dereference
a stream ring at the invalid stream_id 0.
ep->stream_info->stream_rings[0] doesn't point to a ring.
Start looping stream_id from 1 like in all the other places in the driver,
and check that the ring exists before trying to kill URBs on it.
Reported-by: rocko r <rockorequin@xxxxxxxxx>
Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/host/xhci-ring.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -856,13 +856,16 @@ static void xhci_kill_endpoint_urbs(stru
(ep->ep_state & EP_GETTING_NO_STREAMS)) {
int stream_id;
- for (stream_id = 0; stream_id < ep->stream_info->num_streams;
+ for (stream_id = 1; stream_id < ep->stream_info->num_streams;
stream_id++) {
+ ring = ep->stream_info->stream_rings[stream_id];
+ if (!ring)
+ continue;
+
xhci_dbg_trace(xhci, trace_xhci_dbg_cancel_urb,
"Killing URBs for slot ID %u, ep index %u, stream %u",
- slot_id, ep_index, stream_id + 1);
- xhci_kill_ring_urbs(xhci,
- ep->stream_info->stream_rings[stream_id]);
+ slot_id, ep_index, stream_id);
+ xhci_kill_ring_urbs(xhci, ring);
}
} else {
ring = ep->ring;