From 16b0801ba6b25a5660f2ba30fef35e9cc81fe9c0 Mon Sep 17 00:00:00 2001
From: Henning Westerholt <hw@skalatan.de>
Date: Thu, 5 Mar 2020 11:19:52 +0100
Subject: [PATCH] core: fix a crash in cfg parser related to invalid syntax
 cases

(cherry picked from commit 54a0aeee9d30ee85045150d8ad5b75f7a4b71d15)
---
 src/core/cfg.y | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/core/cfg.y b/src/core/cfg.y
index 502ca92e0cf..b26af8b4a3f 100644
--- a/src/core/cfg.y
+++ b/src/core/cfg.y
@@ -2861,7 +2861,7 @@ rval_expr: rval						{ $$=$1;
 		| rval_expr rve_cmpop rval_expr %prec GT { $$=mk_rve2( $2, $1, $3);}
 		| rval_expr rve_equalop rval_expr %prec EQUAL_T {
 			/* comparing with $null => treat as defined or !defined */
-			if($3->op==RVE_RVAL_OP && $3->left.rval.type==RV_PVAR
+			if($3 != NULL && $3->op==RVE_RVAL_OP && $3->left.rval.type==RV_PVAR
 					&& $3->left.rval.v.pvs.type==PVT_NULL) {
 				if($2==RVE_DIFF_OP || $2==RVE_IDIFF_OP
 						|| $2==RVE_STRDIFF_OP) {