From: Guy Harris <guy@alum.mit.edu>
Date: Wed, 12 Nov 2014 00:49:39 +0000 (-0800)
Subject: Do more bounds checking and length checking.
X-Git-Url: https://git.tcpdump.org/tcpdump/commitdiff_plain/74e2f75d1f24f98936ac4935d6a45c4762fe288f

Do more bounds checking and length checking.

Don't run past the end of the captured data, and don't run past the end
of the packet (i.e., don't make the length variable go negative).

Also, stop dissecting if the message length isn't valid.
---

diff --git a/print-olsr.c b/print-olsr.c
index 6fa0d76c..6d2d65f2 100644
--- a/print-olsr.c
+++ b/print-olsr.c
@@ -178,7 +178,7 @@ struct olsr_lq_neighbor6 {
 /*
  * print a neighbor list with LQ extensions.
  */
-static void
+static int
 olsr_print_lq_neighbor4(netdissect_options *ndo,
                         const u_char *msg_data, u_int hello_len)
 {
@@ -187,6 +187,8 @@ olsr_print_lq_neighbor4(netdissect_options *ndo,
     while (hello_len >= sizeof(struct olsr_lq_neighbor4)) {
 
         lq_neighbor = (struct olsr_lq_neighbor4 *)msg_data;
+        if (!ND_TTEST(*lq_neighbor))
+            return (-1);
 
         ND_PRINT((ndo, "\n\t      neighbor %s, link-quality %.2lf%%"
                ", neighbor-link-quality %.2lf%%",
@@ -197,10 +199,11 @@ olsr_print_lq_neighbor4(netdissect_options *ndo,
         msg_data += sizeof(struct olsr_lq_neighbor4);
         hello_len -= sizeof(struct olsr_lq_neighbor4);
     }
+    return (0);
 }
 
 #if INET6
-static void
+static int
 olsr_print_lq_neighbor6(netdissect_options *ndo,
                         const u_char *msg_data, u_int hello_len)
 {
@@ -209,6 +212,8 @@ olsr_print_lq_neighbor6(netdissect_options *ndo,
     while (hello_len >= sizeof(struct olsr_lq_neighbor6)) {
 
         lq_neighbor = (struct olsr_lq_neighbor6 *)msg_data;
+        if (!ND_TTEST(*lq_neighbor))
+            return (-1);
 
         ND_PRINT((ndo, "\n\t      neighbor %s, link-quality %.2lf%%"
                ", neighbor-link-quality %.2lf%%",
@@ -219,13 +224,14 @@ olsr_print_lq_neighbor6(netdissect_options *ndo,
         msg_data += sizeof(struct olsr_lq_neighbor6);
         hello_len -= sizeof(struct olsr_lq_neighbor6);
     }
+    return (0);
 }
 #endif /* INET6 */
 
 /*
  * print a neighbor list.
  */
-static void
+static int
 olsr_print_neighbor(netdissect_options *ndo,
                     const u_char *msg_data, u_int hello_len)
 {
@@ -236,6 +242,8 @@ olsr_print_neighbor(netdissect_options *ndo,
 
     while (hello_len >= sizeof(struct in_addr)) {
 
+        if (!ND_TTEST2(*msg_data, sizeof(struct in_addr)))
+            return (-1);
         /* print 4 neighbors per line */
 
         ND_PRINT((ndo, "%s%s", ipaddr_string(ndo, msg_data),
@@ -244,6 +252,7 @@ olsr_print_neighbor(netdissect_options *ndo,
         msg_data += sizeof(struct in_addr);
         hello_len -= sizeof(struct in_addr);
     }
+    return (0);
 }
 
 
@@ -326,6 +335,9 @@ olsr_print(netdissect_options *ndo,
                     ME_TO_DOUBLE(msgptr.v6->vtime),
                     EXTRACT_16BITS(msgptr.v6->msg_seq),
                     msg_len, (msg_len_valid == 0) ? " (invalid)" : ""));
+            if (!msg_len_valid) {
+                return;
+            }
 
             msg_tlen = msg_len - sizeof(struct olsr_msg6);
             msg_data = tptr + sizeof(struct olsr_msg6);
@@ -354,6 +366,9 @@ olsr_print(netdissect_options *ndo,
                     ME_TO_DOUBLE(msgptr.v4->vtime),
                     EXTRACT_16BITS(msgptr.v4->msg_seq),
                     msg_len, (msg_len_valid == 0) ? " (invalid)" : ""));
+            if (!msg_len_valid) {
+                return;
+            }
 
             msg_tlen = msg_len - sizeof(struct olsr_msg4);
             msg_data = tptr + sizeof(struct olsr_msg4);
@@ -362,6 +377,8 @@ olsr_print(netdissect_options *ndo,
         switch (msg_type) {
         case OLSR_HELLO_MSG:
         case OLSR_HELLO_LQ_MSG:
+            if (msg_tlen < sizeof(struct olsr_hello))
+                goto trunc;
             ND_TCHECK2(*msg_data, sizeof(struct olsr_hello));
 
             ptr.hello = (struct olsr_hello *)msg_data;
@@ -401,15 +418,21 @@ olsr_print(netdissect_options *ndo,
                 msg_tlen -= sizeof(struct olsr_hello_link);
                 hello_len -= sizeof(struct olsr_hello_link);
 
+                ND_TCHECK2(*msg_data, hello_len);
                 if (msg_type == OLSR_HELLO_MSG) {
-                    olsr_print_neighbor(ndo, msg_data, hello_len);
+                    if (olsr_print_neighbor(ndo, msg_data, hello_len) == -1)
+                        goto trunc;
                 } else {
 #if INET6
-                    if (is_ipv6)
-                        olsr_print_lq_neighbor6(ndo, msg_data, hello_len);
-                    else
+                    if (is_ipv6) {
+                        if (olsr_print_lq_neighbor6(ndo, msg_data, hello_len) == -1)
+                            goto trunc;
+                    } else
 #endif
-                        olsr_print_lq_neighbor4(ndo, msg_data, hello_len);
+                    {
+                        if (olsr_print_lq_neighbor4(ndo, msg_data, hello_len) == -1)
+                            goto trunc;
+                    }
                 }
 
                 msg_data += hello_len;
@@ -419,6 +442,8 @@ olsr_print(netdissect_options *ndo,
 
         case OLSR_TC_MSG:
         case OLSR_TC_LQ_MSG:
+            if (msg_tlen < sizeof(struct olsr_tc))
+                goto trunc;
             ND_TCHECK2(*msg_data, sizeof(struct olsr_tc));
 
             ptr.tc = (struct olsr_tc *)msg_data;
@@ -428,14 +453,19 @@ olsr_print(netdissect_options *ndo,
             msg_tlen -= sizeof(struct olsr_tc);
 
             if (msg_type == OLSR_TC_MSG) {
-                olsr_print_neighbor(ndo, msg_data, msg_tlen);
+                if (olsr_print_neighbor(ndo, msg_data, msg_tlen) == -1)
+                    goto trunc;
             } else {
 #if INET6
-                if (is_ipv6)
-                    olsr_print_lq_neighbor6(ndo, msg_data, msg_tlen);
-                else
+                if (is_ipv6) {
+                    if (olsr_print_lq_neighbor6(ndo, msg_data, msg_tlen) == -1)
+                        goto trunc;
+                } else
 #endif
-                    olsr_print_lq_neighbor4(ndo, msg_data, msg_tlen);
+                {
+                    if (olsr_print_lq_neighbor4(ndo, msg_data, msg_tlen) == -1)
+                        goto trunc;
+                }
             }
             break;