mwifiex: potential integer underflow in mwifiex_ret_wmm_get_status()

Before we loop for next iteration we adjust the buffer pointer and
"resp_len":

		curr += (tlv_len + sizeof(tlv_hdr->header));
		resp_len -= (tlv_len + sizeof(tlv_hdr->header));

If "resp_len" gets set to negative then it counts as a high positive
value.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/mwifiex/wmm.c

@@ -722,6 +722,9 @@ int mwifiex_ret_wmm_get_status(struct mwifiex_private *priv,
 		tlv_hdr = (struct mwifiex_ie_types_data *) curr;
 		tlv_len = le16_to_cpu(tlv_hdr->header.len);
 
+		if (resp_len < tlv_len + sizeof(tlv_hdr->header))
+			break;
+
 		switch (le16_to_cpu(tlv_hdr->header.type)) {
 		case TLV_TYPE_WMMQSTATUS:
 			tlv_wmm_qstatus =