linux-kernel - Re: [PATCH v2] x86/mm/KASLR: EFI region is mistakenly included into KASLR VA space for randomization

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:   Fri, 24 Mar 2017 09:42:40 +0000
From:   Ard Biesheuvel <ard.biesheuvel@...aro.org>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Ingo Molnar <mingo@...nel.org>, Dave Young <dyoung@...hat.com>,
        Baoquan He <bhe@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
        Thomas Garnier <thgarnie@...gle.com>,
        Kees Cook <keescook@...omium.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Bhupesh Sharma <bhsharma@...hat.com>
Subject: Re: [PATCH v2] x86/mm/KASLR: EFI region is mistakenly included into
 KASLR VA space for randomization

On 24 March 2017 at 09:40, Borislav Petkov <bp@...en8.de> wrote:
> On Fri, Mar 24, 2017 at 09:37:36AM +0000, Ard Biesheuvel wrote:
>> No. It is the firmware's EFI code, and the virtual translation applied
>> by the OS is made known to the firmware by means of a call into the
>> runtime service SetVirtualAddressMap().
>
> We can still randomize within those 64G before calling
> SetVirtualAddressMap(). The question is, do we want to or need to, even?
>

That is a different matter. If the regions are only mapped while
runtime services invocations are in progress (as we do on ARM), I am
not sure if it matters that much, given how rarely that occurs in
normal use.