linux-kernel - Re: [PATCH] exit: Use READ_ONCE() for all oops/warn limit reads

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Date:   Mon, 19 Dec 2022 12:39:49 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Kees Cook <keescook@...omium.org>
Cc:     "Eric W. Biederman" <ebiederm@...ssion.com>,
        Jann Horn <jannh@...gle.com>, Arnd Bergmann <arnd@...db.de>,
        Petr Mladek <pmladek@...e.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Marco Elver <elver@...gle.com>,
        tangmeng <tangmeng@...ontech.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Tiezhu Yang <yangtiezhu@...ngson.cn>,
        Stafford Horne <shorne@...il.com>,
        "Guilherme G. Piccoli" <gpiccoli@...lia.com>,
        John Ogness <john.ogness@...utronix.de>,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH] exit: Use READ_ONCE() for all oops/warn limit reads

On Fri, Dec 16, 2022 at 12:30:28PM -0800, Kees Cook wrote:
> Use a temporary variable to take full advantage of READ_ONCE() behavior.
> Without this, the report (and even the test) might be out of sync with
> the initial test.
> 
> Reported-by: Peter Zijlstra <peterz@...radead.org>
> Link: https://lore.kernel.org/lkml/Y5x7GXeluFmZ8E0E@hirez.programming.kicks-ass.net
> Fixes: 9fc9e278a5c0 ("panic: Introduce warn_limit")
> Fixes: d4ccd54d28d3 ("exit: Put an upper limit on how often we can oops")

Thanks!

Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>