linux-kernel - Re: [PATCH 3/4] randstruct: Disable randomization of ACPICA structs

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Message-ID: <CAGXu5jLr5mS0x6faLm-XM3G18vShjuGgjd0OcdTRn=qxgsXtwQ@mail.gmail.com>
Date:   Thu, 22 Jun 2017 17:20:31 -0700
From:   Kees Cook <keescook@...omium.org>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     Lv Zheng <lv.zheng@...el.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Christoph Hellwig <hch@...radead.org>,
        "kernel-hardening@...ts.openwall.com" 
        <kernel-hardening@...ts.openwall.com>,
        LKML <linux-kernel@...r.kernel.org>, Len Brown <lenb@...nel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Robert Moore <robert.moore@...el.com>
Subject: Re: [PATCH 3/4] randstruct: Disable randomization of ACPICA structs

On Thu, Jun 22, 2017 at 4:59 PM, Rafael J. Wysocki <rjw@...ysocki.net> wrote:
> On Thursday, June 22, 2017 04:57:39 PM Kees Cook wrote:
>> On Tue, Jun 20, 2017 at 2:34 PM, Rafael J. Wysocki <rafael@...nel.org> wrote:
>> > On Tue, Jun 20, 2017 at 10:35 PM, Christoph Hellwig <hch@...radead.org> wrote:
>> >> On Tue, Jun 20, 2017 at 12:25:53PM -0700, Kees Cook wrote:
>> >>> Can you send the patch to https://github.com/acpica/acpica ? My change
>> >>> was finally accepted, so this whole issue will go away on the next
>> >>> refresh. Until then, I don't want to block the entire automatic
>> >>> structure selection logic of randstruct on a three-function table. :)
>> >>
>> >> I do not have a github account and no such thing is required for kernel
>> >> development.
>> >
>> > It isn't required for the ACPICA material either.
>> >
>> > You just need to CC the ACPICA maintainers, as per MAINTAINERS, on
>> > your ACPICA patches.  They pick up stuff that looks good to them.
>> >
>> > And we tend to prefer routing ACPICA changes through the upstream,
>> > because failing to do so usually turns out to be painful in the long
>> > term.  I don't think it is unreasonable to ask for cooperation in that
>> > respect.
>>
>> I'd like to unblock randstruct, so what's the easiest way to move
>> this? My version of changes have already landed upstream in ACPICA,
>> but I don't know how frequently they get flushed back into the kernel.
>
> Usually, when there's a new ACPICA release, but occasionally that happens
> faster.
>
> Which commit in upstream ACPICA is this?

https://github.com/acpica/acpica/commit/2058b3bf5deecb9644d676703bd97d1bce5e612a

>> I can't turn on randstruct auto-selection in -next without either
>> ACPICA using (or not needing) designated initializers or just
>> blacklisting it in the randstruct plugin itself. I would much prefer
>> the latter as the problem is solved in ACPICA upstream already but
>> just isn't in the kernel yet, and I want to get testing of the
>> auto-selection ASAP. Once it's in the kernel I can drop the blacklist.
>>
>> Christoph: how about a middle ground where randstruct blacklists
>> ACPICA in -next and if ACPICA is fixed by the time the merge window
>> opens, I'll drop the blacklist. That gets the testing coverage without
>> what you see as an ugly hack right now. I just really don't want to
>> waste any more time on this since there are SO many other randomized
>> structures I'd like to be sure are getting testing.
>>
>> Alternatively, if the ACPICA folks Ack Christoph's patch, I can carry
>> that in the randstruct tree for -next instead?
>
> Maybe we can simply forward port the ACPICA commit right away.
>
> Lv, can you take care of this, please?

That would be great, thanks!

-Kees

-- 
Kees Cook
Pixel Security