tree df6c8bbae1e165624af259bb8de5c1d77a4aeb60
parent 28bedb5ae463b9f7e5195cbc93f1795e374bdef8
author Lu Baolu <baolu.lu@linux.intel.com> 1483460926 +0200
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1483461452 +0100

usb: xhci: fix possible wild pointer

handle_cmd_completion() frees a command structure which might be still
referenced by xhci->current_cmd.
This might cause problem when xhci->current_cmd is accessed after that.

A real-life case could be like this. The host takes a very long time to
respond to a command, and the command timer is fired at the same time
when the command completion event arrives. The command completion
handler frees xhci->current_cmd before the timer function can grab
xhci->lock. Afterward, timer function grabs the lock and go ahead with
checking and setting members of xhci->current_cmd.

Cc: <stable@vger.kernel.org> # v3.16+
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>