linux-kernel - Re: [PATCH 5/8] membarrier, kthread: Use

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]

Date:   Wed, 16 Jun 2021 14:08:31 -0400 (EDT)
From:   Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To:     Andy Lutomirski <luto@...nel.org>
Cc:     x86 <x86@...nel.org>, Dave Hansen <dave.hansen@...el.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-mm <linux-mm@...ck.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH 5/8] membarrier, kthread: Use _ONCE accessors for
 task->mm

----- On Jun 15, 2021, at 11:21 PM, Andy Lutomirski luto@...nel.org wrote:

> membarrier reads cpu_rq(remote cpu)->curr->mm without locking.  Use
> READ_ONCE() and WRITE_ONCE() to remove the data races.

I notice that kernel/exit.c:exit_mm() also has:

        current->mm = NULL;

I suspect you may want to add a WRITE_ONCE() there as well ?

Thanks,

Mathieu


-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com