[PATCH 4.9 61/96] usbip: vudc_tx: fix v_send_ret_submit() vulnerability to null xfer buffer

From: Greg Kroah-Hartman
Date: Mon Jan 15 2018 - 08:40:32 EST


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

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

From: Shuah Khan <shuahkh@xxxxxxxxxxxxxxx>

commit 5fd77a3a0e408c23ab4002a57db980e46bc16e72 upstream.

v_send_ret_submit() handles urb with a 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.

Signed-off-by: Shuah Khan <shuahkh@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/usb/usbip/vudc_tx.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

--- a/drivers/usb/usbip/vudc_tx.c
+++ b/drivers/usb/usbip/vudc_tx.c
@@ -97,6 +97,13 @@ static int v_send_ret_submit(struct vudc
memset(&pdu_header, 0, sizeof(pdu_header));
memset(&msg, 0, sizeof(msg));

+ if (urb->actual_length > 0 && !urb->transfer_buffer) {
+ dev_err(&udc->gadget.dev,
+ "urb: actual_length %d transfer_buffer null\n",
+ urb->actual_length);
+ return -1;
+ }
+
if (urb_p->type == USB_ENDPOINT_XFER_ISOC)
iovnum = 2 + urb->number_of_packets;
else
@@ -112,8 +119,8 @@ static int v_send_ret_submit(struct vudc

/* 1. setup usbip_header */
setup_ret_submit_pdu(&pdu_header, urb_p);
- usbip_dbg_stub_tx("setup txdata seqnum: %d urb: %p\n",
- pdu_header.base.seqnum, urb);
+ usbip_dbg_stub_tx("setup txdata seqnum: %d\n",
+ pdu_header.base.seqnum);
usbip_header_correct_endian(&pdu_header, 1);

iov[iovnum].iov_base = &pdu_header;