linux-kernel - Re: [PATCH] can: bcm: delay release of struct bcm_op after synchronize

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <20210619201238.isat2vojezfkfndf@pengutronix.de>
Date:   Sat, 19 Jun 2021 22:12:38 +0200
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Thadeu Lima de Souza Cascardo <cascardo@...onical.com>
Cc:     linux-can@...r.kernel.org,
        Oliver Hartkopp <socketcan@...tkopp.net>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        syzbot+0f7e7e5e2f4f40fa89c0@...kaller.appspotmail.com,
        Norbert Slusarek <nslusarek@....net>
Subject: Re: [PATCH] can: bcm: delay release of struct bcm_op after
 synchronize_rcu

On 19.06.2021 13:18:13, Thadeu Lima de Souza Cascardo wrote:
> can_rx_register callbacks may be called concurrently to the call to
> can_rx_unregister. The callbacks and callback data, though, are protected by
> RCU and the struct sock reference count.
> 
> So the callback data is really attached to the life of sk, meaning that it
> should be released on sk_destruct. However, bcm_remove_op calls tasklet_kill,
> and RCU callbacks may be called under RCU softirq, so that cannot be used on
> kernels before the introduction of HRTIMER_MODE_SOFT.
> 
> However, bcm_rx_handler is called under RCU protection, so after calling
> can_rx_unregister, we may call synchronize_rcu in order to wait for any RCU
> read-side critical sections to finish. That is, bcm_rx_handler won't be called
> anymore for those ops. So, we only free them, after we do that synchronize_rcu.
> 
> Reported-by: syzbot+0f7e7e5e2f4f40fa89c0@...kaller.appspotmail.com
> Reported-by: Norbert Slusarek <nslusarek@....net>
> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@...onical.com>

Added to linux-can/testing.

Thanks,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-5555 |

Download attachment "signature.asc" of type "application/pgp-signature" (489 bytes)