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Date: Thu, 23 Jul 2026 09:12:48 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: John Ericson <John.Ericson@Obsidian.Systems>
Cc: Kuniyuki Iwashima <kuniyu@google.com>, "David S . Miller"
 <davem@davemloft.net>, Eric Dumazet <edumazet@google.com>, Paolo Abeni
 <pabeni@redhat.com>, John Ericson <mail@johnericson.me>, Simon Horman
 <horms@kernel.org>, Christian Brauner <brauner@kernel.org>, David
 Rheinsberg <david@readahead.eu>, Cong Wang <cwang@multikernel.io>, Sergei
 Zimmerman <sergei@zimmerman.foo>, netdev@vger.kernel.org,
 linux-kernel@vger.kernel.org
Subject: Re: [PATCH net v3 1/2] af_unix: fix listen() succeeding on sockets
 in the wrong state
Message-ID: <20260723091248.6acaa173@kernel.org>
In-Reply-To: <20260718182903.2295560-1-John.Ericson@Obsidian.Systems>
References: <20260718182903.2295560-1-John.Ericson@Obsidian.Systems>
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On Sat, 18 Jul 2026 14:29:01 -0400 John Ericson wrote:
> Commit fd0a109a0f6b ("net, pidfs: prepare for handing out pidfds for
> reaped sk->sk_peer_pid") inserted a prepare_peercred() call between err
> = -EINVAL and the socket-state check in unix_listen(). Since
> prepare_peercred() leaves err at 0 on success, listen() on an AF_UNIX
> socket that is not in TCP_CLOSE or TCP_LISTEN state (e.g. one that is
> already connected) now silently returns success without doing anything,
> instead of failing with EINVAL as it did before.

As the bug proves this

	err = x
	if (cond)
		goto bla;

is a fragile pattern. People do this to avoid the extra braces AFAIU
but it's not worth it. Can you move the error setting before the jumps
please?

	if (cond) {
		err = x;
		goto bla;
	}
-- 
pw-bot: cr