From: mbuhl <mbuhl@openbsd.org>
Date: Mon, 13 Mar 2023 14:58:01 +0000 (+0000)
Subject: Fix potential underflow when printing STP data.
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=9fd53d3a184b4b9a66557587baff934243fa4451;p=openbsd

Fix potential underflow when printing STP data.
Reported by Peter J. Philipp
ok claudio
---

diff --git a/usr.sbin/tcpdump/print-stp.c b/usr.sbin/tcpdump/print-stp.c
index d9087c75400..07a4b8f5aa6 100644
--- a/usr.sbin/tcpdump/print-stp.c
+++ b/usr.sbin/tcpdump/print-stp.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: print-stp.c,v 1.10 2021/12/01 18:28:46 deraadt Exp $	*/
+/*	$OpenBSD: print-stp.c,v 1.11 2023/03/13 14:58:01 mbuhl Exp $	*/
 
 /*
  * Copyright (c) 2000 Jason L. Wright (jason@thought.net)
@@ -99,6 +99,8 @@ stp_print(p, len)
 	else if (p[0] == LLCSAP_SNAP && p[1] == LLCSAP_SNAP && p[2] == LLC_UI) {
 		proto = STP_PROTO_SSTP;
 		printf("SSTP");
+		if (len < 8)
+			goto truncated;
 		p += 5;
 		len -= 5;
 	} else {