Index: head/lib/libc/rpc/rpc_generic.c
===================================================================
--- head/lib/libc/rpc/rpc_generic.c
+++ head/lib/libc/rpc/rpc_generic.c
@@ -609,6 +609,8 @@
 
 	switch (af) {
 	case AF_INET:
+		if (nbuf->len < sizeof(*sin))
+			return NULL;
 		sin = nbuf->buf;
 		if (inet_ntop(af, &sin->sin_addr, namebuf, sizeof namebuf)
 		    == NULL)
@@ -620,6 +622,8 @@
 		break;
 #ifdef INET6
 	case AF_INET6:
+		if (nbuf->len < sizeof(*sin6))
+			return NULL;
 		sin6 = nbuf->buf;
 		if (inet_ntop(af, &sin6->sin6_addr, namebuf6, sizeof namebuf6)
 		    == NULL)
@@ -658,6 +662,10 @@
 
 	port = 0;
 	sin = NULL;
+
+	if (uaddr == NULL)
+		return NULL;
+
 	addrstr = strdup(uaddr);
 	if (addrstr == NULL)
 		return NULL;
Index: head/lib/libc/rpc/rpcb_prot.c
===================================================================
--- head/lib/libc/rpc/rpcb_prot.c
+++ head/lib/libc/rpc/rpcb_prot.c
@@ -51,6 +51,7 @@
 #include <rpc/types.h>
 #include <rpc/xdr.h>
 #include <rpc/rpcb_prot.h>
+#include <rpc/rpc_com.h>
 #include "un-namespace.h"
 
 bool_t
@@ -62,13 +63,13 @@
 	if (!xdr_rpcvers(xdrs, &objp->r_vers)) {
 		return (FALSE);
 	}
-	if (!xdr_string(xdrs, &objp->r_netid, (u_int)~0)) {
+	if (!xdr_string(xdrs, &objp->r_netid, RPC_MAXDATASIZE)) {
 		return (FALSE);
 	}
-	if (!xdr_string(xdrs, &objp->r_addr, (u_int)~0)) {
+	if (!xdr_string(xdrs, &objp->r_addr, RPC_MAXDATASIZE)) {
 		return (FALSE);
 	}
-	if (!xdr_string(xdrs, &objp->r_owner, (u_int)~0)) {
+	if (!xdr_string(xdrs, &objp->r_owner, RPC_MAXDATASIZE)) {
 		return (FALSE);
 	}
 	return (TRUE);
@@ -162,19 +163,19 @@
 bool_t
 xdr_rpcb_entry(XDR *xdrs, rpcb_entry *objp)
 {
-	if (!xdr_string(xdrs, &objp->r_maddr, (u_int)~0)) {
+	if (!xdr_string(xdrs, &objp->r_maddr, RPC_MAXDATASIZE)) {
 		return (FALSE);
 	}
-	if (!xdr_string(xdrs, &objp->r_nc_netid, (u_int)~0)) {
+	if (!xdr_string(xdrs, &objp->r_nc_netid, RPC_MAXDATASIZE)) {
 		return (FALSE);
 	}
 	if (!xdr_u_int32_t(xdrs, &objp->r_nc_semantics)) {
 		return (FALSE);
 	}
-	if (!xdr_string(xdrs, &objp->r_nc_protofmly, (u_int)~0)) {
+	if (!xdr_string(xdrs, &objp->r_nc_protofmly, RPC_MAXDATASIZE)) {
 		return (FALSE);
 	}
-	if (!xdr_string(xdrs, &objp->r_nc_proto, (u_int)~0)) {
+	if (!xdr_string(xdrs, &objp->r_nc_proto, RPC_MAXDATASIZE)) {
 		return (FALSE);
 	}
 	return (TRUE);
@@ -289,7 +290,7 @@
 	bool_t dummy;
 	struct r_rpcb_rmtcallres *objp = (struct r_rpcb_rmtcallres *)(void *)p;
 
-	if (!xdr_string(xdrs, &objp->addr, (u_int)~0)) {
+	if (!xdr_string(xdrs, &objp->addr, RPC_MAXDATASIZE)) {
 		return (FALSE);
 	}
 	if (!xdr_u_int(xdrs, &objp->results.results_len)) {
Index: head/lib/libc/rpc/rpcb_st_xdr.c
===================================================================
--- head/lib/libc/rpc/rpcb_st_xdr.c
+++ head/lib/libc/rpc/rpcb_st_xdr.c
@@ -42,6 +42,7 @@
 
 #include "namespace.h"
 #include <rpc/rpc.h>
+#include <rpc/rpc_com.h>
 #include "un-namespace.h"
 
 /* Link list of all the stats about getport and getaddr */
@@ -63,7 +64,7 @@
 	    if (!xdr_int(xdrs, &objp->failure)) {
 		return (FALSE);
 	    }
-	    if (!xdr_string(xdrs, &objp->netid, (u_int)~0)) {
+	    if (!xdr_string(xdrs, &objp->netid, RPC_MAXDATASIZE)) {
 		return (FALSE);
 	    }
 
@@ -115,7 +116,7 @@
 		IXDR_PUT_INT32(buf, objp->failure);
 		IXDR_PUT_INT32(buf, objp->indirect);
 	}
-	if (!xdr_string(xdrs, &objp->netid, (u_int)~0)) {
+	if (!xdr_string(xdrs, &objp->netid, RPC_MAXDATASIZE)) {
 		return (FALSE);
 	}
 	pnext = &objp->next;
@@ -154,7 +155,7 @@
 		objp->failure = (int)IXDR_GET_INT32(buf);
 		objp->indirect = (int)IXDR_GET_INT32(buf);
 	}
-	if (!xdr_string(xdrs, &objp->netid, (u_int)~0)) {
+	if (!xdr_string(xdrs, &objp->netid, RPC_MAXDATASIZE)) {
 		return (FALSE);
 	}
 	if (!xdr_pointer(xdrs, (char **) pnext,
@@ -182,7 +183,7 @@
 	if (!xdr_int(xdrs, &objp->indirect)) {
 		return (FALSE);
 	}
-	if (!xdr_string(xdrs, &objp->netid, (u_int)~0)) {
+	if (!xdr_string(xdrs, &objp->netid, RPC_MAXDATASIZE)) {
 		return (FALSE);
 	}
 	if (!xdr_pointer(xdrs, (char **) pnext,
Index: head/lib/libc/xdr/xdr.c
===================================================================
--- head/lib/libc/xdr/xdr.c
+++ head/lib/libc/xdr/xdr.c
@@ -52,6 +52,8 @@
 #include <stdlib.h>
 #include <string.h>
 
+#include <rpc/rpc.h>
+#include <rpc/rpc_com.h>
 #include <rpc/types.h>
 #include <rpc/xdr.h>
 #include "un-namespace.h"
@@ -64,7 +66,6 @@
  */
 #define XDR_FALSE	((long) 0)
 #define XDR_TRUE	((long) 1)
-#define LASTUNSIGNED	((u_int) 0-1)
 
 /*
  * for unit alignment
@@ -561,6 +562,7 @@
 {
 	char *sp = *cpp;  /* sp is the actual string pointer */
 	u_int nodesize;
+	bool_t ret, allocated = FALSE;
 
 	/*
 	 * first deal with the length since xdr bytes are counted
@@ -584,6 +586,7 @@
 		}
 		if (sp == NULL) {
 			*cpp = sp = mem_alloc(nodesize);
+			allocated = TRUE;
 		}
 		if (sp == NULL) {
 			warnx("xdr_bytes: out of memory");
@@ -592,7 +595,14 @@
 		/* FALLTHROUGH */
 
 	case XDR_ENCODE:
-		return (xdr_opaque(xdrs, sp, nodesize));
+		ret = xdr_opaque(xdrs, sp, nodesize);
+		if ((xdrs->x_op == XDR_DECODE) && (ret == FALSE)) {
+			if (allocated == TRUE) {
+				free(sp);
+				*cpp = NULL;
+			}
+		}
+		return (ret);
 
 	case XDR_FREE:
 		if (sp != NULL) {
@@ -683,6 +693,7 @@
 	char *sp = *cpp;  /* sp is the actual string pointer */
 	u_int size;
 	u_int nodesize;
+	bool_t ret, allocated = FALSE;
 
 	/*
 	 * first deal with the length since xdr strings are counted-strings
@@ -716,8 +727,10 @@
 		if (nodesize == 0) {
 			return (TRUE);
 		}
-		if (sp == NULL)
+		if (sp == NULL) {
 			*cpp = sp = mem_alloc(nodesize);
+			allocated = TRUE;
+		}
 		if (sp == NULL) {
 			warnx("xdr_string: out of memory");
 			return (FALSE);
@@ -726,7 +739,14 @@
 		/* FALLTHROUGH */
 
 	case XDR_ENCODE:
-		return (xdr_opaque(xdrs, sp, size));
+		ret = xdr_opaque(xdrs, sp, size);
+		if ((xdrs->x_op == XDR_DECODE) && (ret == FALSE)) {
+			if (allocated == TRUE) {
+				free(sp);
+				*cpp = NULL;
+			}
+		}
+		return (ret);
 
 	case XDR_FREE:
 		mem_free(sp, nodesize);
@@ -744,7 +764,7 @@
 bool_t
 xdr_wrapstring(XDR *xdrs, char **cpp)
 {
-	return xdr_string(xdrs, cpp, LASTUNSIGNED);
+	return xdr_string(xdrs, cpp, RPC_MAXDATASIZE);
 }
 
 /*
Index: head/sys/rpc/rpc_generic.c
===================================================================
--- head/sys/rpc/rpc_generic.c
+++ head/sys/rpc/rpc_generic.c
@@ -311,6 +311,8 @@
 
 	switch (af) {
 	case AF_INET:
+		if (nbuf->len < sizeof(*sin))
+			return NULL;
 		sin = nbuf->buf;
 		if (inet_ntop(af, &sin->sin_addr, namebuf, sizeof namebuf)
 		    == NULL)
@@ -323,6 +325,8 @@
 		break;
 #ifdef INET6
 	case AF_INET6:
+		if (nbuf->len < sizeof(*sin6))
+			return NULL;
 		sin6 = nbuf->buf;
 		if (inet_ntop(af, &sin6->sin6_addr, namebuf6, sizeof namebuf6)
 		    == NULL)
@@ -366,6 +370,10 @@
 
 	port = 0;
 	sin = NULL;
+
+	if (uaddr == NULL)
+		return NULL;
+
 	addrstr = strdup(uaddr, M_RPC);
 	if (addrstr == NULL)
 		return NULL;
Index: head/sys/rpc/rpcb_clnt.c
===================================================================
--- head/sys/rpc/rpcb_clnt.c
+++ head/sys/rpc/rpcb_clnt.c
@@ -1287,6 +1287,11 @@
 		return (FALSE);
 	}
 	pp = &objp->buf;
+
+	if (objp->maxlen > RPC_MAXDATASIZE) {
+		return (FALSE);
+	}
+
 	dummy = xdr_bytes(xdrs, (char **) pp,
 			(u_int *)&(objp->len), objp->maxlen);
 	return (dummy);
Index: head/sys/rpc/rpcb_prot.c
===================================================================
--- head/sys/rpc/rpcb_prot.c
+++ head/sys/rpc/rpcb_prot.c
@@ -52,6 +52,7 @@
 #include <sys/malloc.h>
 
 #include <rpc/rpc.h>
+#include <rpc/rpc_com.h>
 #include <rpc/rpcb_prot.h>
 
 bool_t
@@ -74,13 +75,13 @@
 	if (!xdr_uint32_t(xdrs, &objp->r_vers)) {
 		return (FALSE);
 	}
-	if (!xdr_string(xdrs, &objp->r_netid, (u_int)~0)) {
+	if (!xdr_string(xdrs, &objp->r_netid, RPC_MAXDATASIZE)) {
 		return (FALSE);
 	}
-	if (!xdr_string(xdrs, &objp->r_addr, (u_int)~0)) {
+	if (!xdr_string(xdrs, &objp->r_addr, RPC_MAXDATASIZE)) {
 		return (FALSE);
 	}
-	if (!xdr_string(xdrs, &objp->r_owner, (u_int)~0)) {
+	if (!xdr_string(xdrs, &objp->r_owner, RPC_MAXDATASIZE)) {
 		return (FALSE);
 	}
 	return (TRUE);
@@ -175,19 +176,19 @@
 bool_t
 xdr_rpcb_entry(XDR *xdrs, rpcb_entry *objp)
 {
-	if (!xdr_string(xdrs, &objp->r_maddr, (u_int)~0)) {
+	if (!xdr_string(xdrs, &objp->r_maddr, RPC_MAXDATASIZE)) {
 		return (FALSE);
 	}
-	if (!xdr_string(xdrs, &objp->r_nc_netid, (u_int)~0)) {
+	if (!xdr_string(xdrs, &objp->r_nc_netid, RPC_MAXDATASIZE)) {
 		return (FALSE);
 	}
 	if (!xdr_uint32_t(xdrs, &objp->r_nc_semantics)) {
 		return (FALSE);
 	}
-	if (!xdr_string(xdrs, &objp->r_nc_protofmly, (u_int)~0)) {
+	if (!xdr_string(xdrs, &objp->r_nc_protofmly, RPC_MAXDATASIZE)) {
 		return (FALSE);
 	}
-	if (!xdr_string(xdrs, &objp->r_nc_proto, (u_int)~0)) {
+	if (!xdr_string(xdrs, &objp->r_nc_proto, RPC_MAXDATASIZE)) {
 		return (FALSE);
 	}
 	return (TRUE);
Index: head/sys/xdr/xdr.c
===================================================================
--- head/sys/xdr/xdr.c
+++ head/sys/xdr/xdr.c
@@ -51,6 +51,8 @@
 #include <sys/kernel.h>
 #include <sys/malloc.h>
 
+#include <rpc/rpc.h>
+#include <rpc/rpc_com.h>
 #include <rpc/types.h>
 #include <rpc/xdr.h>
 
@@ -62,7 +64,6 @@
  */
 #define XDR_FALSE	((long) 0)
 #define XDR_TRUE	((long) 1)
-#define LASTUNSIGNED	((u_int) 0-1)
 
 /*
  * for unit alignment
@@ -503,6 +504,7 @@
 {
 	char *sp = *cpp;  /* sp is the actual string pointer */
 	u_int nodesize;
+	bool_t ret, allocated = FALSE;
 
 	/*
 	 * first deal with the length since xdr bytes are counted
@@ -526,6 +528,7 @@
 		}
 		if (sp == NULL) {
 			*cpp = sp = mem_alloc(nodesize);
+			allocated = TRUE;
 		}
 		if (sp == NULL) {
 			printf("xdr_bytes: out of memory");
@@ -534,7 +537,14 @@
 		/* FALLTHROUGH */
 
 	case XDR_ENCODE:
-		return (xdr_opaque(xdrs, sp, nodesize));
+		ret = xdr_opaque(xdrs, sp, nodesize);
+		if ((xdrs->x_op == XDR_DECODE) && (ret == FALSE)) {
+			if (allocated == TRUE) {
+				mem_free(sp, nodesize);
+				*cpp = NULL;
+			}
+		}
+		return (ret);
 
 	case XDR_FREE:
 		if (sp != NULL) {
@@ -622,6 +632,7 @@
 	char *sp = *cpp;  /* sp is the actual string pointer */
 	u_int size;
 	u_int nodesize;
+	bool_t ret, allocated = FALSE;
 
 	/*
 	 * first deal with the length since xdr strings are counted-strings
@@ -655,8 +666,10 @@
 		if (nodesize == 0) {
 			return (TRUE);
 		}
-		if (sp == NULL)
+		if (sp == NULL) {
 			*cpp = sp = mem_alloc(nodesize);
+			allocated = TRUE;
+		}
 		if (sp == NULL) {
 			printf("xdr_string: out of memory");
 			return (FALSE);
@@ -665,7 +678,14 @@
 		/* FALLTHROUGH */
 
 	case XDR_ENCODE:
-		return (xdr_opaque(xdrs, sp, size));
+		ret = xdr_opaque(xdrs, sp, size);
+		if ((xdrs->x_op == XDR_DECODE) && (ret == FALSE)) {
+			if (allocated == TRUE) {
+				mem_free(sp, nodesize);
+				*cpp = NULL;
+			}
+		}
+		return (ret);
 
 	case XDR_FREE:
 		mem_free(sp, nodesize);
@@ -683,7 +703,7 @@
 bool_t
 xdr_wrapstring(XDR *xdrs, char **cpp)
 {
-	return xdr_string(xdrs, cpp, LASTUNSIGNED);
+	return xdr_string(xdrs, cpp, RPC_MAXDATASIZE);
 }
 
 /*
Index: head/usr.sbin/rpcbind/rpcb_svc_com.c
===================================================================
--- head/usr.sbin/rpcbind/rpcb_svc_com.c
+++ head/usr.sbin/rpcbind/rpcb_svc_com.c
@@ -55,6 +55,7 @@
 #include <stdio.h>
 #ifdef PORTMAP
 #include <netinet/in.h>
+#include <rpc/rpc_com.h>
 #include <rpc/pmap_prot.h>
 #endif /* PORTMAP */
 #include <string.h>
@@ -418,7 +419,8 @@
 static bool_t
 xdr_encap_parms(XDR *xdrs, struct encap_parms *epp)
 {
-	return (xdr_bytes(xdrs, &(epp->args), (u_int *) &(epp->arglen), ~0));
+	return (xdr_bytes(xdrs, &(epp->args), (u_int *) &(epp->arglen),
+	    RPC_MAXDATASIZE));
 }
 
 /*