[PATCH 4.4 024/101] usb: host: xhci: Fix possible wild pointer when handling abort command

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Baolin Wang <baolin.wang@xxxxxxxxxx>

commit 2a7cfdf37b7c08ac29df4c62ea5ccb01474b6597 upstream.

When current command was supposed to be aborted, host will free the command
in handle_cmd_completion() function. But it might be still referenced by
xhci->current_cmd, which need to set NULL.

Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxx>
Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/usb/host/xhci-ring.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -1365,8 +1365,11 @@ static void handle_cmd_completion(struct
 	 */
 	if (cmd_comp_code == COMP_CMD_ABORT) {
 		xhci->cmd_ring_state = CMD_RING_STATE_STOPPED;
-		if (cmd->status == COMP_CMD_ABORT)
+		if (cmd->status == COMP_CMD_ABORT) {
+			if (xhci->current_cmd == cmd)
+				xhci->current_cmd = NULL;
 			goto event_handled;
+		}
 	}
 
 	cmd_type = TRB_FIELD_TO_TYPE(le32_to_cpu(cmd_trb->generic.field[3]));