From: Tom Yu <tlyu@mit.edu>
Date: Tue, 29 Mar 2005 21:21:14 +0000 (+0000)
Subject: fix MITKRB5-SA-2005-001 telnet client vuln
X-Git-Tag: ms-bug-test-20060525~296
X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=08c52c1b3c2dfdd825dfa671cebff141697fc0d7;p=krb5.git

fix MITKRB5-SA-2005-001 telnet client vuln

	* telnet.c (slc_add_reply, slc_end_reply): Fix buffer overflow
	vulnerability by checking lengths.
	(env_opt_add): Ensure buffer allocation is sufficiently large,
	accounting for expansion during IAC quoting.

ticket: new
tags: pullup
version_reported: 1.4
target_version: 1.4.1
component: telnet

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@17162 dc483132-0cff-0310-8789-dd5450dbe970
---

diff --git a/src/appl/telnet/telnet/ChangeLog b/src/appl/telnet/telnet/ChangeLog
index 91d52591a..e223a7750 100644
--- a/src/appl/telnet/telnet/ChangeLog
+++ b/src/appl/telnet/telnet/ChangeLog
@@ -1,3 +1,10 @@
+2005-03-28  Tom Yu  <tlyu@mit.edu>
+
+	* telnet.c (slc_add_reply, slc_end_reply): Fix buffer overflow
+	vulnerability by checking lengths.
+	(env_opt_add): Ensure buffer allocation is sufficiently large,
+	accounting for expansion during IAC quoting.
+
 2004-03-04  Ken Raeburn  <raeburn@mit.edu>
 
 	* configure.in: Deleted; configure this dir from parent now.
diff --git a/src/appl/telnet/telnet/telnet.c b/src/appl/telnet/telnet/telnet.c
index a92bbd5d1..6215fc1e9 100644
--- a/src/appl/telnet/telnet/telnet.c
+++ b/src/appl/telnet/telnet/telnet.c
@@ -1475,6 +1475,8 @@ slc_add_reply(func, flags, value)
 	unsigned char flags;
 	cc_t value;
 {
+	if ((slc_replyp - slc_reply) + 6 > sizeof(slc_reply))
+		return;
 	if ((*slc_replyp++ = func) == IAC)
 		*slc_replyp++ = IAC;
 	if ((*slc_replyp++ = flags) == IAC)
@@ -1488,11 +1490,12 @@ slc_end_reply()
 {
     register int len;
 
-    *slc_replyp++ = IAC;
-    *slc_replyp++ = SE;
     len = slc_replyp - slc_reply;
-    if (len <= 6)
+    if (len <= 4 || (len + 2 > sizeof(slc_reply)))
 	return;
+    *slc_replyp++ = IAC;
+    *slc_replyp++ = SE;
+    len += 2;
     if (NETROOM() > len) {
 	ring_supply_data(&netoring, slc_reply, slc_replyp - slc_reply);
 	printsub('>', &slc_reply[2], slc_replyp - slc_reply - 2);
@@ -1645,6 +1648,7 @@ env_opt_add(ep)
 	register unsigned char *ep;
 {
 	register unsigned char *vp, c;
+	unsigned int len, olen, elen;
 
 	if (opt_reply == NULL)		/*XXX*/
 		return;			/*XXX*/
@@ -1662,19 +1666,19 @@ env_opt_add(ep)
 		return;
 	}
 	vp = env_getvalue(ep);
-	if (opt_replyp + (vp ? strlen((char *)vp) : 0) +
-				strlen((char *)ep) + 6 > opt_replyend)
+	elen = 2 * (vp ? strlen((char *)vp) : 0) +
+		2 * strlen((char *)ep) + 6;
+	if ((opt_replyend - opt_replyp) < elen)
 	{
-		register unsigned int len;
-		opt_replyend += OPT_REPLY_SIZE;
-		len = opt_replyend - opt_reply;
+		len = opt_replyend - opt_reply + elen;
+		olen = opt_replyp - opt_reply;
 		opt_reply = (unsigned char *)realloc(opt_reply, len);
 		if (opt_reply == NULL) {
 /*@*/			printf("env_opt_add: realloc() failed!!!\n");
 			opt_reply = opt_replyp = opt_replyend = NULL;
 			return;
 		}
-		opt_replyp = opt_reply + len - (opt_replyend - opt_replyp);
+		opt_replyp = opt_reply + olen;
 		opt_replyend = opt_reply + len;
 	}
 	if (opt_welldefined((char *) ep))