From: Jakub Kicinski <kuba@kernel.org>
To: Eric Dumazet <edumazet@google.com>
Cc: Yizhou Zhao <zhaoyz24@mails.tsinghua.edu.cn>,
netdev@vger.kernel.org, "David S. Miller" <davem@davemloft.net>,
Paolo Abeni <pabeni@redhat.com>, Simon Horman <horms@kernel.org>,
Kees Cook <kees@kernel.org>, Kito Xu <veritas501@foxmail.com>,
linux-kernel@vger.kernel.org,
Yuxiang Yang <yangyx22@mails.tsinghua.edu.cn>,
Ao Wang <wangao@seu.edu.cn>, Xuewei Feng <fengxw06@126.com>,
Qi Li <qli01@tsinghua.edu.cn>, Ke Xu <xuke@tsinghua.edu.cn>,
stable@vger.kernel.org
Subject: Re: [PATCH net] appletalk: Hold socket reference in atalk_rcv()
Date: Mon, 15 Jun 2026 10:23:08 -0700 [thread overview]
Message-ID: <20260615102308.49f90c0e@kernel.org> (raw)
In-Reply-To: <CANn89iLwy0tsB5wMrREnGSvmPrThyCkjHEz0hpWbCiTJSG0NCA@mail.gmail.com>
On Mon, 15 Jun 2026 09:53:59 -0700 Eric Dumazet wrote:
> > atalk_search_socket() walks the global atalk_sockets list while holding
> > atalk_sockets_lock, but it returns the matching socket after dropping the
> > lock without taking a reference. atalk_rcv() then passes that pointer to
> > sock_queue_rcv_skb().
> >
> > That leaves a race with close(). A concurrent atalk_release() can orphan
> > the socket, remove it from atalk_sockets, and drop the final reference via
> > atalk_destroy_socket(), freeing the socket before atalk_rcv() queues the
> > incoming skb.
> >
> > On a KASAN-enabled kernel this can be reproduced by racing AppleTalk DDP
> > delivery on loopback against close/rebind of the destination DGRAM socket:
> >
> > BUG: KASAN: slab-use-after-free in selinux_socket_sock_rcv_skb()
> > sk_filter_trim_cap()
> > sock_queue_rcv_skb_reason()
> > atalk_rcv()
> > snap_rcv()
> > llc_rcv()
> >
> > Take a reference on the selected socket before dropping
> > atalk_sockets_lock, and put it after sock_queue_rcv_skb() has finished.
> > This keeps the socket alive for the receive path without changing socket
> > lookup semantics. A malformed or racing receive still drops the skb on
> > queueing failure as before.
>
> No idea why linux still carries appletalk.
>
> MacOS dropped it 20 years ago.
Yes. Let me try to move it to mod-orphan.
prev parent reply other threads:[~2026-06-15 17:23 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-14 9:52 [PATCH net] appletalk: Hold socket reference in atalk_rcv() Yizhou Zhao
2026-06-15 16:48 ` Simon Horman
2026-06-15 16:53 ` Eric Dumazet
2026-06-15 17:23 ` Jakub Kicinski [this message]
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