Fix CVE-2015-8629 (xdr_nullstring() doesn't check for terminating null
character).

From upstream git repository, commit
df17a1224a3406f57477bcd372c61e04c0e5a5bb.

diff --git a/src/lib/kadm5/kadm_rpc_xdr.c b/src/lib/kadm5/kadm_rpc_xdr.c
index 2bef858..ba67084 100644
--- a/src/lib/kadm5/kadm_rpc_xdr.c
+++ b/src/lib/kadm5/kadm_rpc_xdr.c
@@ -64,7 +64,14 @@ bool_t xdr_nullstring(XDR *xdrs, char **objp)
 		    return FALSE;
 	       }
 	  }
-	  return (xdr_opaque(xdrs, *objp, size));
+	  if (!xdr_opaque(xdrs, *objp, size))
+		  return FALSE;
+	  /* Check that the unmarshalled bytes are a C string. */
+	  if ((*objp)[size - 1] != '\0')
+		  return FALSE;
+	  if (memchr(*objp, '\0', size - 1) != NULL)
+		  return FALSE;
+	  return TRUE;
 
      case XDR_ENCODE:
 	  if (size != 0)
-- 
2.6.3