LDP: Fix an undefined behavior at runtime

The error was:
print-ldp.c:557:13: runtime error: unsigned integer overflow: 32 - 34
cannot be represented in type 'unsigned int'

1 files changed, 8 insertions, 3 deletions

diff --git a/print-ldp.c b/print-ldp.c
index 680a7e1e..49379f0d 100644
--- a/print-ldp.c
+++ b/print-ldp.c
@@ -211,7 +211,7 @@ static const struct tok ldp_fec_martini_ifparm_vccv_cv_values[] = {
     { 0, NULL}
 };
 
-static int ldp_pdu_print(netdissect_options *, const u_char *);
+static u_int ldp_pdu_print(netdissect_options *, const u_char *);
 
 /*
  * ldp tlv header
@@ -547,19 +547,24 @@ void
 ldp_print(netdissect_options *ndo,
           const u_char *pptr, u_int len)
 {
-    int processed;
+    u_int processed;
 
     ndo->ndo_protocol = "ldp";
     while (len > (sizeof(struct ldp_common_header) + sizeof(struct ldp_msg_header))) {
         processed = ldp_pdu_print(ndo, pptr);
         if (processed == 0)
             return;
+        if (len < processed) {
+            ND_PRINT(" [remaining length %u < %u]", len, processed);
+            nd_print_invalid(ndo);
+            break;
+        }
         len -= processed;
         pptr += processed;
     }
 }
 
-static int
+static u_int
 ldp_pdu_print(netdissect_options *ndo,
               const u_char *pptr)
 {