usb: gadget: rndis: check size of RNDIS_MSG_SET command

Check the size of the RNDIS_MSG_SET command given to us before
attempting to respond to an invalid message size.
Reported-by: Szymon Heidrich <szymon.heidrich@gmail.com>
Cc: stable@kernel.org
Tested-by: Szymon Heidrich <szymon.heidrich@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/function/rndis.c

@@ -637,14 +637,17 @@ static int rndis_set_response(struct rndis_params *params,
 	rndis_set_cmplt_type *resp;
 	rndis_resp_t *r;
 
+	BufLength = le32_to_cpu(buf->InformationBufferLength);
+	BufOffset = le32_to_cpu(buf->InformationBufferOffset);
+	if ((BufLength > RNDIS_MAX_TOTAL_SIZE) ||
+	    (BufOffset + 8 >= RNDIS_MAX_TOTAL_SIZE))
+		    return -EINVAL;
+
 	r = rndis_add_response(params, sizeof(rndis_set_cmplt_type));
 	if (!r)
 		return -ENOMEM;
 	resp = (rndis_set_cmplt_type *)r->buf;
 
-	BufLength = le32_to_cpu(buf->InformationBufferLength);
-	BufOffset = le32_to_cpu(buf->InformationBufferOffset);
-
 #ifdef	VERBOSE_DEBUG
 	pr_debug("%s: Length: %d\n", __func__, BufLength);
 	pr_debug("%s: Offset: %d\n", __func__, BufOffset);