File 0001-cache-check-for-NULL-chain-in-cache_init.patch of Package nftables.32329

From 6b7b7d5d219dca4465390f4a69096383d17782d3 Mon Sep 17 00:00:00 2001
From: Pablo Neira Ayuso <pablo@netfilter.org>
Date: Thu, 1 Apr 2021 23:15:02 +0200
Subject: [PATCH] cache: check for NULL chain in cache_init()

Another process might race to add chains after chain_cache_init().
The generation check does not help since it comes after cache_init().
NLM_F_DUMP_INTR only guarantees consistency within one single netlink
dump operation, so it does not help either (cache population requires
several netlink dump commands).

Let's be safe and do not assume the chain exists in the cache when
populating the rule cache.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 src/rule.c | 3 +++
 1 file changed, 3 insertions(+)

Index: nftables-0.9.8/src/rule.c
===================================================================
--- nftables-0.9.8.orig/src/rule.c
+++ nftables-0.9.8/src/rule.c
@@ -205,6 +205,9 @@ static int cache_init_objects(struct net
 				if (!chain)
 					chain = chain_binding_lookup(table,
 							rule->handle.chain.name);
+				if (!chain) {
+					return -1;
+				}
 				list_move_tail(&rule->list, &chain->rules);
 			}
 			if (ret < 0)