Validate some counts that may be received from the network:

Check that they are non-negative, and that they are small enough to
avoid integer overflow when used in memory allocation calculations.


git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@11411 ec53bebd-3082-4978-b11e-865c3cabbd6b

kdc/kaserver.c

@@ -186,6 +186,8 @@ krb5_ret_xdr_data(krb5_storage *sp,
     ret = krb5_ret_int32(sp, &size);
     if(ret)
 	return ret;
+    if(size < 0)
+	return ERANGE;
     data->length = size;
     if (size) {
 	u_char foo[4];