EAP-IKEv2: Fix the payload parser

The payload lengths were not properly verified and the first check on
there being enough buffer for the header was practically ignored. The
second check for the full payload would catch length issues, but this is
only after the potential read beyond the buffer. (CID 72687)

Signed-off-by: Jouni Malinen <j@w1.fi>

src/eap_common/ikev2_common.c

@@ -251,7 +251,7 @@ int ikev2_parse_payloads(struct ikev2_payloads *payloads,
 	os_memset(payloads, 0, sizeof(*payloads));
 
 	while (next_payload != IKEV2_PAYLOAD_NO_NEXT_PAYLOAD) {
-		int plen, pdatalen;
+		unsigned int plen, pdatalen;
 		const u8 *pdata;
 		wpa_printf(MSG_DEBUG, "IKEV2: Processing payload %u",
 			   next_payload);
@@ -259,17 +259,18 @@ int ikev2_parse_payloads(struct ikev2_payloads *payloads,
 			wpa_printf(MSG_INFO, "IKEV2:   Too short message for "
 				   "payload header (left=%ld)",
 				   (long) (end - pos));
+			return -1;
 		}
 		phdr = (const struct ikev2_payload_hdr *) pos;
 		plen = WPA_GET_BE16(phdr->payload_length);
-		if (plen < (int) sizeof(*phdr) || pos + plen > end) {
+		if (plen < sizeof(*phdr) || plen > end - pos) {
 			wpa_printf(MSG_INFO, "IKEV2:   Invalid payload header "
 				   "length %d", plen);
 			return -1;
 		}
 
 		wpa_printf(MSG_DEBUG, "IKEV2:   Next Payload: %u  Flags: 0x%x"
-			   "  Payload Length: %d",
+			   "  Payload Length: %u",
 			   phdr->next_payload, phdr->flags, plen);
 
 		pdata = (const u8 *) (phdr + 1);