diff --git a/NeXT/vjcompress.c b/NeXT/vjcompress.c
index 237b1ff..0a0a29a 100644
--- a/NeXT/vjcompress.c
+++ b/NeXT/vjcompress.c
@@ -29,7 +29,7 @@
  * This version is used under SunOS 4.x, DEC Alpha OSF/1, AIX 4.x,
  * and SVR4 systems including Solaris 2.
  *
- * $Id: vjcompress.c,v 1.1 1995/12/18 03:30:20 paulus Exp $
+ * $Id: vjcompress.c,v 1.2 1996/05/24 07:04:06 paulus Exp $
  */
 
 #include <sys/types.h>
@@ -439,7 +439,12 @@ vj_uncompress_uncomp(buf, comp)
     register struct ip *ip;
 
     ip = (struct ip *) buf;
-    if (ip->ip_p >= MAX_STATES) {
+    hlen = getip_hl(*ip) << 2;
+    if (ip->ip_p >= MAX_STATES
+	|| hlen + sizeof(struct tcphdr) > buflen
+	|| (hlen += getth_off(*((struct tcphdr *)&((char *)ip)[hlen])) << 2)
+	    > buflen
+	|| hlen > MAX_HDR) {
 	comp->flags |= VJF_TOSS;
 	INCR(vjs_errorin);
 	return (0);
@@ -447,9 +452,6 @@ vj_uncompress_uncomp(buf, comp)
     cs = &comp->rstate[comp->last_recv = ip->ip_p];
     comp->flags &=~ VJF_TOSS;
     ip->ip_p = IPPROTO_TCP;
-    hlen = getip_hl(*ip);
-    hlen += getth_off(*((struct tcphdr *)&((int *)ip)[hlen]));
-    hlen <<= 2;
     BCOPY(ip, &cs->cs_ip, hlen);
     cs->cs_hlen = hlen;
     INCR(vjs_uncompressedin);
diff --git a/freebsd-2.0/pppcompress.c b/freebsd-2.0/pppcompress.c
index 9967eb7..383ca58 100644
--- a/freebsd-2.0/pppcompress.c
+++ b/freebsd-2.0/pppcompress.c
@@ -40,7 +40,7 @@
  * Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989:
  *    - Initial distribution.
  *
- *	$Id: pppcompress.c,v 1.1 1994/12/15 22:27:17 paulus Exp $
+ *	$Id: pppcompress.c,v 1.2 1996/05/24 07:04:14 paulus Exp $
  */
   
 #include <sys/types.h>
@@ -471,9 +471,16 @@ vj_uncompress_tcp_core(buf, buflen, total_len, type, comp, hdrp, hlenp)
 		cs = &comp->rstate[comp->last_recv = ip->ip_p];
 		comp->flags &=~ SLF_TOSS;
 		ip->ip_p = IPPROTO_TCP;
-		hlen = ip->ip_hl;
-		hlen += ((struct tcphdr *)&((int *)ip)[hlen])->th_off;
-		hlen <<= 2;
+		/*
+		 * Calculate the size of the TCP/IP header and make sure that
+		 * we don't overflow the space we have available for it.
+		 */
+		hlen = ip->ip_hl << 2;
+		if (hlen + sizeof(struct tcphdr) > buflen)
+			goto bad;
+		hlen += ((struct tcphdr *)&((char *)ip)[hlen])->th_off << 2;
+		if (hlen > MAX_HDR || hlen > buflen)
+			goto bad;
 		BCOPY(ip, &cs->cs_ip, hlen);
 		cs->cs_hlen = hlen;
 		INCR(sls_uncompressedin)
diff --git a/modules/vjcompress.c b/modules/vjcompress.c
index 2507573..eecbef5 100644
--- a/modules/vjcompress.c
+++ b/modules/vjcompress.c
@@ -29,7 +29,7 @@
  * This version is used under SunOS 4.x, DEC Alpha OSF/1, AIX 4.x,
  * and SVR4 systems including Solaris 2.
  *
- * $Id: vjcompress.c,v 1.7 1995/12/11 02:57:49 paulus Exp $
+ * $Id: vjcompress.c,v 1.8 1996/05/24 07:04:26 paulus Exp $
  */
 
 #include <sys/types.h>
@@ -430,8 +430,9 @@ vj_uncompress_err(comp)
  * "Uncompress" a packet of type TYPE_UNCOMPRESSED_TCP.
  */
 int
-vj_uncompress_uncomp(buf, comp)
+vj_uncompress_uncomp(buf, buflen, comp)
     u_char *buf;
+    int buflen;
     struct vjcompress *comp;
 {
     register u_int hlen;
@@ -439,7 +440,12 @@ vj_uncompress_uncomp(buf, comp)
     register struct ip *ip;
 
     ip = (struct ip *) buf;
-    if (ip->ip_p >= MAX_STATES) {
+    hlen = getip_hl(*ip) << 2;
+    if (ip->ip_p >= MAX_STATES
+	|| hlen + sizeof(struct tcphdr) > buflen
+	|| (hlen += getth_off(*((struct tcphdr *)&((char *)ip)[hlen])) << 2)
+	    > buflen
+	|| hlen > MAX_HDR) {
 	comp->flags |= VJF_TOSS;
 	INCR(vjs_errorin);
 	return (0);
@@ -447,9 +453,6 @@ vj_uncompress_uncomp(buf, comp)
     cs = &comp->rstate[comp->last_recv = ip->ip_p];
     comp->flags &=~ VJF_TOSS;
     ip->ip_p = IPPROTO_TCP;
-    hlen = getip_hl(*ip);
-    hlen += getth_off(*((struct tcphdr *)&((int *)ip)[hlen]));
-    hlen <<= 2;
     BCOPY(ip, &cs->cs_ip, hlen);
     cs->cs_hlen = hlen;
     INCR(vjs_uncompressedin);
diff --git a/netbsd-1.1/slcompress.c b/netbsd-1.1/slcompress.c
index 7a0e24e..c46c57f 100644
--- a/netbsd-1.1/slcompress.c
+++ b/netbsd-1.1/slcompress.c
@@ -1,4 +1,4 @@
-/*	$Id: slcompress.c,v 1.2 1996/04/04 04:17:44 paulus Exp $	*/
+/*	$Id: slcompress.c,v 1.3 1996/05/24 07:04:47 paulus Exp $	*/
 
 /*
  * Copyright (c) 1989, 1993, 1994
@@ -477,9 +477,16 @@ sl_uncompress_tcp_core(buf, buflen, total_len, type, comp, hdrp, hlenp)
 		cs = &comp->rstate[comp->last_recv = ip->ip_p];
 		comp->flags &=~ SLF_TOSS;
 		ip->ip_p = IPPROTO_TCP;
-		hlen = ip->ip_hl;
-		hlen += ((struct tcphdr *)&((int32_t *)ip)[hlen])->th_off;
-		hlen <<= 2;
+		/*
+		 * Calculate the size of the TCP/IP header and make sure that
+		 * we don't overflow the space we have available for it.
+		 */
+		hlen = ip->ip_hl << 2;
+		if (hlen + sizeof(struct tcphdr) > buflen)
+			goto bad;
+		hlen += ((struct tcphdr *)&((char *)ip)[hlen])->th_off << 2;
+		if (hlen > MAX_HDR || hlen > buflen)
+			goto bad;
 		BCOPY(ip, &cs->cs_ip, hlen);
 		cs->cs_hlen = hlen;
 		INCR(sls_uncompressedin)
diff --git a/ultrix/slcompress.c b/ultrix/slcompress.c
index ecbdf3b..1cbdd3f 100644
--- a/ultrix/slcompress.c
+++ b/ultrix/slcompress.c
@@ -24,7 +24,7 @@
  * so that the entire packet being decompressed doesn't have
  * to be in contiguous memory (just the compressed header).
  *
- * $Id: slcompress.c,v 1.2 1994/11/28 01:42:00 paulus Exp $
+ * $Id: slcompress.c,v 1.3 1996/05/24 07:04:55 paulus Exp $
  */
 
 #include "../h/types.h"
@@ -482,9 +482,16 @@ sl_uncompress_tcp_core(buf, buflen, total_len, type, comp, hdrp, hlenp)
 		cs = &comp->rstate[comp->last_recv = ip->ip_p];
 		comp->flags &=~ SLF_TOSS;
 		ip->ip_p = IPPROTO_TCP;
-		hlen = ip->ip_hl;
-		hlen += ((struct tcphdr *)&((int *)ip)[hlen])->th_off;
-		hlen <<= 2;
+		/*
+		 * Calculate the size of the TCP/IP header and make sure that
+		 * we don't overflow the space we have available for it.
+		 */
+		hlen = ip->ip_hl << 2;
+		if (hlen + sizeof(struct tcphdr) > buflen)
+			goto bad;
+		hlen += ((struct tcphdr *)&((char *)ip)[hlen])->th_off << 2;
+		if (hlen > MAX_HDR || hlen > buflen)
+			goto bad;
 		BCOPY(ip, &cs->cs_ip, hlen);
 		cs->cs_hlen = hlen;
 		INCR(sls_uncompressedin)