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Message-ID: <CABBYNZJCbYnxodwXAeq8F9NerzGWFva0OG6SfUWfJ_Grz=Xq6Q@mail.gmail.com>
Date: Fri, 28 Apr 2023 14:24:40 -0700
From: Luiz Augusto von Dentz <luiz.dentz@...il.com>
To: Li Tuo <islituo@...il.com>
Cc: marcel@...tmann.org, johan.hedberg@...il.com,
"David S. Miller" <davem@...emloft.net>, edumazet@...gle.com,
Jakub Kicinski <kuba@...nel.org>, pabeni@...hat.com,
linux-bluetooth@...r.kernel.org, netdev@...r.kernel.org,
Linux Kernel <linux-kernel@...r.kernel.org>,
baijiaju1990@...look.com
Subject: Re: [BUG][RESEND] Bluetooth: L2CAP: possible data race in __sco_sock_close()
Hi,
On Fri, Apr 28, 2023 at 3:27 AM Li Tuo <islituo@...il.com> wrote:
>
> Hello,
>
> Our static analysis tool finds a possible data race in the l2cap protocol
> in Linux 6.3.0-rc7:
>
> In most calling contexts, the variable sk->sk_socket is accessed
> with holding the lock sk->sk_callback_lock. Here is an example:
>
> l2cap_sock_accept() --> Line 346 in net/bluetooth/l2cap_sock.c
> bt_accept_dequeue() --> Line 368 in net/bluetooth/l2cap_sock.c
> sock_graft() --> Line 240 in net/bluetooth/af_bluetooth.c
> write_lock_bh(&sk->sk_callback_lock); --> Line 2081 in include/net/sock.h (Lock sk->sk_callback_lock)
> sk_set_socket() --> Line 2084 in include/net/sock.h
> sk->sk_socket = sock; --> Line 2054 in include/net/sock.h (Access sk->sk_socket)
>
> However, in the following calling context:
>
> sco_sock_shutdown() --> Line 1227 in net/bluetooth/sco.c
> __sco_sock_close() --> Line 1243 in net/bluetooth/sco.c
> BT_DBG(..., sk->sk_socket); --> Line 431 in net/bluetooth/sco.c (Access sk->sk_socket)
>
> the variable sk->sk_socket is accessed without holding the lock
> sk->sk_callback_lock, and thus a data race may occur.
>
> Reported-by: BassCheck <bass@...a.edu.cn>
Need to check in detail what it means to hold the sk_callback_lock,
btw is this static analysis tool of yours something public that we can
use in our CI to detect these problems?
--
Luiz Augusto von Dentz
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