linux-kernel - Re: [PATCH V2] posix-timers: Protect posix clock array access against speculation

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Message-ID: <CAPcyv4heWRhy4U23xGZ1-BzjWu5JNm1x=6nnnUeiSFZ4LbTQUA@mail.gmail.com>
Date:   Wed, 7 Mar 2018 10:13:48 -0800
From:   Dan Williams <dan.j.williams@...el.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Rasmus Villemoes <rasmus.villemoes@...vas.dk>,
        LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        David Woodhouse <dwmw@...zon.co.uk>,
        Greg KH <gregkh@...uxfoundation.org>
Subject: Re: [PATCH V2] posix-timers: Protect posix clock array access against speculation

On Thu, Feb 15, 2018 at 9:01 AM, Peter Zijlstra <peterz@...radead.org> wrote:
> On Thu, Feb 15, 2018 at 05:21:55PM +0100, Thomas Gleixner wrote:
>> The clockid argument of clockid_to_kclock() comes straight from user space
>> via various syscalls and is used as index into the posix_clocks array.
>>
>> Protect it against spectre v1 array out of bounds speculation. Remove the
>> redundant check for !posix_clock[id] as this is another source for
>> speculation and does not provide any advantage over the return
>> posix_clock[id] path which returns NULL in that case anyway.
>>
>> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
>> Cc: stable@...r.kernel.org
>
> Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
>

Curious where this ended up, I don't see it on tip/master. In any event:

Acked-by: Dan Williams <dan.j.williams@...el.com>