usbip: fix stub_send_ret_submit() vulnerability to null transfer_buffer

stub_send_ret_submit() handles urb with a potential null transfer_buffer,
when it replays a packet with potential malicious data that could contain
a null buffer. Add a check for the condition when actual_length > 0 and
transfer_buffer is null.

Reported-by: Secunia Research <vuln@secunia.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/usbip/stub_tx.c b/drivers/usb/usbip/stub_tx.c
index b18bce9..53172b1 100644 (file)
--- a/drivers/usb/usbip/stub_tx.c
+++ b/drivers/usb/usbip/stub_tx.c
@@ -167,6 +167,13 @@ static int stub_send_ret_submit(struct stub_device *sdev)
                memset(&pdu_header, 0, sizeof(pdu_header));
                memset(&msg, 0, sizeof(msg));
 
+               if (urb->actual_length > 0 && !urb->transfer_buffer) {
+                       dev_err(&sdev->udev->dev,
+                               "urb: actual_length %d transfer_buffer null\n",
+                               urb->actual_length);
+                       return -1;
+               }
+
                if (usb_pipetype(urb->pipe) == PIPE_ISOCHRONOUS)
                        iovnum = 2 + urb->number_of_packets;
                else