linux-kernel - Re: [PATCH] cpu/hotplug: Serialize callback invocations proper

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

Message-ID: <1489513067.2676.9.camel@sandisk.com>
Date:   Tue, 14 Mar 2017 17:38:00 +0000
From:   Bart Van Assche <Bart.VanAssche@...disk.com>
To:     "bigeasy@...utronix.de" <bigeasy@...utronix.de>
CC:     "tglx@...utronix.de" <tglx@...utronix.de>,
        "torvalds@...ux-foundation.org" <torvalds@...ux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "mingo@...nel.org" <mingo@...nel.org>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "hpa@...or.com" <hpa@...or.com>
Subject: Re: [PATCH] cpu/hotplug: Serialize callback invocations proper

On Tue, 2017-03-14 at 16:06 +0100, Sebastian Andrzej Siewior wrote:
> The setup/remove_state/instance() functions in the hotplug core code are
> serialized against concurrent CPU hotplug, but unfortunately not serialized
> against themself.
> 
> As a consequence a concurrent invocation of these function results in
> corruption of the callback machinery because two instances try to invoke
> callbacks on remote cpus at the same time. This results in missing callback
> invocations and initiator threads waiting forever on the completion.
> 
> The obvious solution to replace get_cpu_online() with cpu_hotplug_begin()
> is not possible because at least one callsite calls into these functions
> from a get_online_cpu() locked region.
> 
> Extend the protection scope of the cpuhp_state_mutex from solely protecting
> the state arrays to cover the callback invocation machinery as well.
> 
> Reported-by: Bart Van Assche <Bart.VanAssche@...disk.com>
> Fixes: 5b7aa87e0482 ("cpu/hotplug: Implement setup/removal interface")
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>

Tested-by: Bart Van Assche <Bart.VanAssche@...disk.com>

So this regression was introduced in kernel v4.6? Anyway, thanks for the patch!

Bart.