netdev - [PATCH v2 net 1/5] tcp: Restart iteration after removing reqsk in inet_twsk

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Date: Mon, 26 Feb 2024 17:10:37 -0800
From: Kuniyuki Iwashima <kuniyu@...zon.com>
To: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
	<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>, Allison Henderson <allison.henderson@...cle.com>
CC: Kuniyuki Iwashima <kuniyu@...zon.com>, Kuniyuki Iwashima
	<kuni1840@...il.com>, <netdev@...r.kernel.org>, <linux-rdma@...r.kernel.org>,
	<rds-devel@....oracle.com>
Subject: [PATCH v2 net 1/5] tcp: Restart iteration after removing reqsk in inet_twsk_purge().

Commit 740ea3c4a0b2 ("tcp: Clean up kernel listener's reqsk in
inet_twsk_purge()") added changes in inet_twsk_purge() to purge
reqsk in per-netns ehash during netns dismantle.

inet_csk_reqsk_queue_drop_and_put() will remove reqsk from per-netns
ehash, but the iteration uses sk_nulls_for_each_rcu(), which is not
safe.

After removing reqsk, we need to restart iteration.

Note that we need not check net->ns.count here because per-netns
ehash does not have reqsk in other live netns.

This change will be removed by the following patch.

Fixes: 740ea3c4a0b2 ("tcp: Clean up kernel listener's reqsk in inet_twsk_purge()")
Reported-by: Eric Dumazet <edumazet@...gle.com>
Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
---
 net/ipv4/inet_timewait_sock.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/ipv4/inet_timewait_sock.c b/net/ipv4/inet_timewait_sock.c
index 5befa4de5b24..00cbebaa2c68 100644
--- a/net/ipv4/inet_timewait_sock.c
+++ b/net/ipv4/inet_timewait_sock.c
@@ -287,6 +287,8 @@ void inet_twsk_purge(struct inet_hashinfo *hashinfo, int family)
 					struct request_sock *req = inet_reqsk(sk);
 
 					inet_csk_reqsk_queue_drop_and_put(req->rsk_listener, req);
+
+					goto restart;
 				}
 
 				continue;
-- 
2.30.2