netdev - Re: [PATCH v2 net-next 00/14] af

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Message-ID: <CANn89i+oURrHhvODH0U9gzR869r_3EK5zuRBNYAV_Frrj_3GRA@mail.gmail.com>
Date: Fri, 16 Feb 2024 22:28:11 +0100
From: Eric Dumazet <edumazet@...gle.com>
To: Kuniyuki Iwashima <kuniyu@...zon.com>
Cc: "David S. Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>, Kuniyuki Iwashima <kuni1840@...il.com>, netdev@...r.kernel.org
Subject: Re: [PATCH v2 net-next 00/14] af_unix: Rework GC.

On Fri, Feb 16, 2024 at 10:06 PM Kuniyuki Iwashima <kuniyu@...zon.com> wrote:
>
> When we pass a file descriptor to an AF_UNIX socket via SCM_RIGTHS,
> the underlying struct file of the inflight fd gets its refcount bumped.
> If the fd is of an AF_UNIX socket, we need to track it in case it forms
> cyclic references.
>
> Let's say we send a fd of AF_UNIX socket A to B and vice versa and
> close() both sockets.
>
> When created, each socket's struct file initially has one reference.
> After the fd exchange, both refcounts are bumped up to 2.  Then, close()
> decreases both to 1.  From this point on, no one can touch the file/socket.

Note that I have pending syzbot reports about af_unix. (apparently
syzbot found its way with SO_PEEK_OFF)

I would prefer we wait a bit before reworking the whole thing.