linux-kernel - Re: [patch V2 01/16] x86/ptrace: Prevent truncation of bitmap size

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Message-ID: <CALCETrWcDpoX-gkFBP8NkRyizbS+=3PcD_x6r6pXVAGoWO6-EA@mail.gmail.com>
Date:   Tue, 12 Nov 2019 07:34:38 -0800
From:   Andy Lutomirski <luto@...nel.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, X86 ML <x86@...nel.org>,
        Linus Torvalds <torvalds@...uxfoundation.org>,
        Andy Lutomirski <luto@...nel.org>,
        Stephen Hemminger <stephen@...workplumber.org>,
        Willy Tarreau <w@....eu>, Juergen Gross <jgross@...e.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...nel.org>
Subject: Re: [patch V2 01/16] x86/ptrace: Prevent truncation of bitmap size

On Mon, Nov 11, 2019 at 2:36 PM Thomas Gleixner <tglx@...utronix.de> wrote:
>
> From: Thomas Gleixner <tglx@...utronix.de>
>
> The active() callback of the IO bitmap regset divides the IO bitmap size by
> the word size (32/64 bit). As the I/O bitmap size is in bytes the active
> check fails for bitmap sizes of 1-3 bytes on 32bit and 1-7 bytes on 64bit.
>
> Use DIV_ROUND_UP() instead.
>
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> Reviewed-by: Ingo Molnar <mingo@...nel.org>

Reviewed-by: Andy Lutomirski <luto@...nel.org>