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From:   Kees Cook <keescook@chromium.org>
Date:   Fri, 19 Apr 2019 10:00:12 -0500
Message-ID: <CAGXu5jJvB-sfsXdZvf8OKSwhmdgANvnsrhZiNGrtraTeQVoOrg@mail.gmail.com>
Subject: Re: [PATCH 2/2] x86/mmap: handle worst-case heap randomization in mmap_base
To:     Ingo Molnar <mingo@kernel.org>
Cc:     "Saidi, Ali" <alisaidi@amazon.com>,
        Kees Cook <keescook@chromium.org>,
        Michal Hocko <mhocko@suse.com>,
        Matthew Wilcox <willy@infradead.org>,
        Jann Horn <jannh@google.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        "Liguori, Anthony" <aliguori@amazon.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        X86 ML <x86@kernel.org>, Will Deacon <will.deacon@arm.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "Woodhouse, David" <dwmw@amazon.co.uk>,
        Andy Lutomirski <luto@kernel.org>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
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On Fri, Apr 19, 2019 at 3:51 AM Ingo Molnar <mingo@kernel.org> wrote:
> I'd suggest incorporating all feedback and sending a v2 series - it's
> much easier to get people's attention via code submitted. ;-)

I sent my patch out, akpm added it to -mm and then xtensa broke, and
it got removed. Soooo... I'm looking at it again now. I think I might
combine the ideas and in the interpreter case bump the entire mmap
base by the brk randomization size. That should make things less
strange and solve the corner case without reducing available address
space in the general case.

-- 
Kees Cook