CVE-2016-7931/Add bounds and length checks.

[tcpdump] / print-tcp.c

diff --git a/print-tcp.c b/print-tcp.c
index 7a04a6ff70b1081a65b95d3ec4b77733fe5e0478..f00ff32514802bebf9dd4ad8df20b300ffeb873a 100644 (file)
--- a/print-tcp.c
+++ b/print-tcp.c
@@ -189,8 +189,6 @@ tcp_print(netdissect_options *ndo,
         sport = EXTRACT_16BITS(&tp->th_sport);
         dport = EXTRACT_16BITS(&tp->th_dport);
 
-        hlen = TH_OFF(tp) * 4;
-
         if (ip6) {
                 if (ip6->ip6_nxt == IPPROTO_TCP) {
                         ND_PRINT((ndo, "%s.%s > %s.%s: ",
@@ -215,14 +213,16 @@ tcp_print(netdissect_options *ndo,
                 }
         }
 
+        ND_TCHECK(*tp);
+
+        hlen = TH_OFF(tp) * 4;
+
         if (hlen < sizeof(*tp)) {
                 ND_PRINT((ndo, " tcp %d [bad hdr length %u - too short, < %lu]",
                              length - hlen, hlen, (unsigned long)sizeof(*tp)));
                 return;
         }
 
-        ND_TCHECK(*tp);
-
         seq = EXTRACT_32BITS(&tp->th_seq);
         ack = EXTRACT_32BITS(&tp->th_ack);
         win = EXTRACT_16BITS(&tp->th_win);
@@ -541,7 +541,7 @@ tcp_print(netdissect_options *ndo,
                                 ND_PRINT((ndo, " keyid %d", *cp++));
                                 datalen = len - 3;
                                 for (i = 0; i < datalen; ++i) {
-                                        LENCHECK(i);
+                                        LENCHECK(i + 1);
                                         ND_PRINT((ndo, "%02x", cp[i]));
                                 }
                                 break;
@@ -609,7 +609,7 @@ tcp_print(netdissect_options *ndo,
                                 if (datalen)
                                         ND_PRINT((ndo, " 0x"));
                                 for (i = 0; i < datalen; ++i) {
-                                        LENCHECK(i);
+                                        LENCHECK(i + 1);
                                         ND_PRINT((ndo, "%02x", cp[i]));
                                 }
                                 break;