netdev - [PATCH net 4/5] netfilter: nf_tables: mark set as dead when unbinding anonymous set with timeout

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Message-Id: <20240307021545.149386-5-pablo@netfilter.org>
Date: Thu,  7 Mar 2024 03:15:44 +0100
From: Pablo Neira Ayuso <pablo@...filter.org>
To: netfilter-devel@...r.kernel.org
Cc: davem@...emloft.net,
	netdev@...r.kernel.org,
	kuba@...nel.org,
	pabeni@...hat.com,
	edumazet@...gle.com,
	fw@...len.de
Subject: [PATCH net 4/5] netfilter: nf_tables: mark set as dead when unbinding anonymous set with timeout

While the rhashtable set gc runs asynchronously, a race allows it to
collect elements from anonymous sets with timeouts while it is being
released from the commit path.

Mingi Cho originally reported this issue in a different path in 6.1.x
with a pipapo set with low timeouts which is not possible upstream since
7395dfacfff6 ("netfilter: nf_tables: use timestamp to check for set
element timeout").

Fix this by setting on the dead flag for anonymous sets to skip async gc
in this case.

According to 08e4c8c5919f ("netfilter: nf_tables: mark newset as dead on
transaction abort"), Florian plans to accelerate abort path by releasing
objects via workqueue, therefore, this sets on the dead flag for abort
path too.

Cc: stable@...r.kernel.org
Fixes: 5f68718b34a5 ("netfilter: nf_tables: GC transaction API to avoid race with control plane")
Reported-by: Mingi Cho <mgcho.minic@...il.com>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
 net/netfilter/nf_tables_api.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index fb07455143a5..1683dc196b59 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -5430,6 +5430,7 @@ static void nf_tables_unbind_set(const struct nft_ctx *ctx, struct nft_set *set,

 	if (list_empty(&set->bindings) && nft_set_is_anonymous(set)) {
 		list_del_rcu(&set->list);
+		set->dead = 1;
 		if (event)
 			nf_tables_set_notify(ctx, set, NFT_MSG_DELSET,
 					     GFP_KERNEL);
-- 
2.30.2