* limit size of buffers to RPC_MAXDATASIZE

 * don't leak memory
 * be more picky about bad parameters

From:

https://raw.githubusercontent.com/guidovranken/rpcbomb/master/libtirpc_patch.txt
https://github.com/guidovranken/rpcbomb/blob/master/rpcbind_patch.txt

via NetBSD.

Reviewed by:	emaste, cem (earlier version)
Differential Revision:	https://reviews.freebsd.org/D10922
MFC after:	3 days

4 files changed, 47 insertions, 17 deletions

diff --git a/lib/libc/rpc/rpc_generic.c b/lib/libc/rpc/rpc_generic.c
index 619fbf17bc52..079837d358ee 100644
--- a/lib/libc/rpc/rpc_generic.c
+++ b/lib/libc/rpc/rpc_generic.c
@@ -609,6 +609,8 @@ __rpc_taddr2uaddr_af(int af, const struct netbuf *nbuf)
 
 	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 @@ __rpc_taddr2uaddr_af(int af, const struct netbuf *nbuf)
 		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 @@ __rpc_uaddr2taddr_af(int af, const char *uaddr)
 
 	port = 0;
 	sin = NULL;
+
+	if (uaddr == NULL)
+		return NULL;
+
 	addrstr = strdup(uaddr);
 	if (addrstr == NULL)
 		return NULL;
diff --git a/lib/libc/rpc/rpcb_prot.c b/lib/libc/rpc/rpcb_prot.c
index c462e192cf03..39a201c6a7ff 100644
--- a/lib/libc/rpc/rpcb_prot.c
+++ b/lib/libc/rpc/rpcb_prot.c
@@ -51,6 +51,7 @@ __FBSDID("$FreeBSD$");
 #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 @@ xdr_rpcb(XDR *xdrs, RPCB *objp)
 	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 @@ xdr_rpcblist(XDR *xdrs, RPCBLIST **rp)
 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 @@ xdr_rpcb_rmtcallres(XDR *xdrs, struct rpcb_rmtcallres *p)
 	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)) {
diff --git a/lib/libc/rpc/rpcb_st_xdr.c b/lib/libc/rpc/rpcb_st_xdr.c
index 9abc0286f109..362184ec79ad 100644
--- a/lib/libc/rpc/rpcb_st_xdr.c
+++ b/lib/libc/rpc/rpcb_st_xdr.c
@@ -42,6 +42,7 @@ __FBSDID("$FreeBSD$");
 
 #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 @@ xdr_rpcbs_addrlist(XDR *xdrs, rpcbs_addrlist *objp)
 	    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 @@ xdr_rpcbs_rmtcalllist(XDR *xdrs, rpcbs_rmtcalllist *objp)
 		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 @@ xdr_rpcbs_rmtcalllist(XDR *xdrs, rpcbs_rmtcalllist *objp)
 		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 @@ xdr_rpcbs_rmtcalllist(XDR *xdrs, rpcbs_rmtcalllist *objp)
 	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,
diff --git a/lib/libc/xdr/xdr.c b/lib/libc/xdr/xdr.c
index 4138171e5023..2d99f58d81bf 100644
--- a/lib/libc/xdr/xdr.c
+++ b/lib/libc/xdr/xdr.c
@@ -52,6 +52,8 @@ __FBSDID("$FreeBSD$");
 #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 @@ typedef u_quad_t        u_longlong_t;   /* ANSI unsigned long long type */
  */
 #define XDR_FALSE	((long) 0)
 #define XDR_TRUE	((long) 1)
-#define LASTUNSIGNED	((u_int) 0-1)
 
 /*
  * for unit alignment
@@ -561,6 +562,7 @@ xdr_bytes(XDR *xdrs, char **cpp, u_int *sizep, u_int maxsize)
 {
 	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 @@ xdr_bytes(XDR *xdrs, char **cpp, u_int *sizep, u_int maxsize)
 		}
 		if (sp == NULL) {
 			*cpp = sp = mem_alloc(nodesize);
+			allocated = TRUE;
 		}
 		if (sp == NULL) {
 			warnx("xdr_bytes: out of memory");
@@ -592,7 +595,14 @@ xdr_bytes(XDR *xdrs, char **cpp, u_int *sizep, u_int maxsize)
 		/* 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 @@ xdr_string(XDR *xdrs, char **cpp, u_int maxsize)
 	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 @@ xdr_string(XDR *xdrs, char **cpp, u_int maxsize)
 		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 @@ xdr_string(XDR *xdrs, char **cpp, u_int maxsize)
 		/* 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 @@ xdr_string(XDR *xdrs, char **cpp, u_int maxsize)
 bool_t
 xdr_wrapstring(XDR *xdrs, char **cpp)
 {
-	return xdr_string(xdrs, cpp, LASTUNSIGNED);
+	return xdr_string(xdrs, cpp, RPC_MAXDATASIZE);
 }
 
 /*