From: Guy Harris <gharris@sonic.net>
Date: Tue, 16 Nov 2021 00:44:46 +0000 (-0800)
Subject: LISP: don't decrement count variables unless we know they're not zero.
X-Git-Tag: tcpdump-4.99.2~164
X-Git-Url: https://git.tcpdump.org/tcpdump/commitdiff_plain/8ff80fe575c15a4c65dae0554690f5afae1d5c81?ds=inline

LISP: don't decrement count variables unless we know they're not zero.

This fixes some undefined behavior warnings.

(cherry picked from commit 913a9fa71293ce12b3c1dea3d93d3a97cf685625)
---

diff --git a/print-lisp.c b/print-lisp.c
index 0012e06e..756fff0f 100644
--- a/print-lisp.c
+++ b/print-lisp.c
@@ -283,8 +283,8 @@ lisp_print(netdissect_options *ndo, const u_char *bp, u_int length)
 		goto invalid;
 
 	/* Print all the EID records */
-	while ((length > packet_offset) && (record_count--)) {
-
+	while ((length > packet_offset) && (record_count != 0)) {
+		record_count--;
 		ND_TCHECK_LEN(packet_iterator + packet_offset,
 			      MAP_REGISTER_EID_LEN);
 		ND_PRINT("\n");
@@ -326,7 +326,8 @@ lisp_print(netdissect_options *ndo, const u_char *bp, u_int length)
 
 		ND_PRINT(" %u locator(s)", loc_count);
 
-		while (loc_count--) {
+		while (loc_count != 0) {
+			loc_count--;
 			ND_TCHECK_LEN(packet_iterator + packet_offset,
 				      MAP_REGISTER_LOC_LEN);
 			lisp_loc = (const lisp_map_register_loc *) (packet_iterator + packet_offset);