netdev - [PATCH net 8/9] netfilter: nf_tables: GC transaction race with netns dismantle

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Date: Wed, 16 Aug 2023 00:29:58 +0200
From: Florian Westphal <fw@...len.de>
To: <netdev@...r.kernel.org>
Cc: Paolo Abeni <pabeni@...hat.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	<netfilter-devel@...r.kernel.org>,
	Pablo Neira Ayuso <pablo@...filter.org>
Subject: [PATCH net 8/9] netfilter: nf_tables: GC transaction race with netns dismantle

From: Pablo Neira Ayuso <pablo@...filter.org>

Use maybe_get_net() since GC workqueue might race with netns exit path.

Fixes: 5f68718b34a5 ("netfilter: nf_tables: GC transaction API to avoid race with control plane")
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
Signed-off-by: Florian Westphal <fw@...len.de>
---
 net/netfilter/nf_tables_api.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 8ac4dd8be1a2..3e841e45f2c0 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -9481,9 +9481,14 @@ struct nft_trans_gc *nft_trans_gc_alloc(struct nft_set *set,
 	if (!trans)
 		return NULL;
 
+	trans->net = maybe_get_net(net);
+	if (!trans->net) {
+		kfree(trans);
+		return NULL;
+	}
+
 	refcount_inc(&set->refs);
 	trans->set = set;
-	trans->net = get_net(net);
 	trans->seq = gc_seq;
 
 	return trans;
-- 
2.41.0