[PATCH 4.14 081/118] usbip: fix vudc_rx: harden CMD_SUBMIT path to handle malicious input

[Greg Kroah-Hartman]

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

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

From: Shuah Khan <shuahkh@xxxxxxxxxxxxxxx>

commit b78d830f0049ef1966dc1e0ebd1ec2a594e2cf25 upstream.

Harden CMD_SUBMIT path to handle malicious input that could trigger
large memory allocations. Add checks to validate transfer_buffer_length
and number_of_packets to protect against bad input requesting for
unbounded memory allocations.

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

---
 drivers/usb/usbip/vudc_rx.c |   19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

--- a/drivers/usb/usbip/vudc_rx.c
+++ b/drivers/usb/usbip/vudc_rx.c
@@ -132,6 +132,25 @@ static int v_recv_cmd_submit(struct vudc
 	urb_p->new = 1;
 	urb_p->seqnum = pdu->base.seqnum;
 
+	if (urb_p->ep->type == USB_ENDPOINT_XFER_ISOC) {
+		/* validate packet size and number of packets */
+		unsigned int maxp, packets, bytes;
+
+		maxp = usb_endpoint_maxp(urb_p->ep->desc);
+		maxp *= usb_endpoint_maxp_mult(urb_p->ep->desc);
+		bytes = pdu->u.cmd_submit.transfer_buffer_length;
+		packets = DIV_ROUND_UP(bytes, maxp);
+
+		if (pdu->u.cmd_submit.number_of_packets < 0 ||
+		    pdu->u.cmd_submit.number_of_packets > packets) {
+			dev_err(&udc->gadget.dev,
+				"CMD_SUBMIT: isoc invalid num packets %d\n",
+				pdu->u.cmd_submit.number_of_packets);
+			ret = -EMSGSIZE;
+			goto free_urbp;
+		}
+	}
+
 	ret = alloc_urb_from_cmd(&urb_p->urb, pdu, urb_p->ep->type);
 	if (ret) {
 		usbip_event_add(&udc->ud, VUDC_EVENT_ERROR_MALLOC);