linux-kernel - Re: Fwd: [crypto:master 60/60] arch/x86/crypto/ghash-clmulni-intel_glue.c:71:25: sparse: cast to restricted _

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Message-ID: <CAKv+Gu_LwiU-WvXeJjOSPJh53g+nKz9x-ZtUP3E02d8UEEyshw@mail.gmail.com>
Date:	Wed, 7 May 2014 08:49:59 +0200
From:	Ard Biesheuvel <ard.biesheuvel@...aro.org>
To:	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>
Cc:	Herbert Xu <herbert@...dor.apana.org.au>,
	"linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: Fwd: [crypto:master 60/60] arch/x86/crypto/ghash-clmulni-intel_glue.c:71:25:
 sparse: cast to restricted __be64

On 7 May 2014 00:42, gregkh@...uxfoundation.org
<gregkh@...uxfoundation.org> wrote:
> On Fri, Apr 11, 2014 at 09:48:42PM +0200, Ard Biesheuvel wrote:
>> On 11 April 2014 18:03, gregkh@...uxfoundation.org
>> <gregkh@...uxfoundation.org> wrote:
>> > On Fri, Apr 04, 2014 at 10:11:19AM +0200, Ard Biesheuvel wrote:
>> >> Greg,
>> >>
>> >> This pertains to commit 8ceee72808d1 (crypto: ghash-clmulni-intel -
>> >> use C implementation for setkey()) that has been pulled by Linus
>> >> during the current merge window.
>> >>
>> >> It is missing two things:
>> >> - a cc to stable annotation
>> >> - a fix for the sparse warning below (change cast from __be64 to __force __be64)
>> >>
>> >> The reason for cc'ing stable on this patch is that it fixes a
>> >> potential data corruption issue where the ghash setkey() method uses
>> >> SSE registers without calling kernel_fpu_begin() first. This issue was
>> >> introduced by 0e1227d356e9b (crypto: ghash - Add PCLMULQDQ accelerated
>> >> implementation).
>> >>
>> >> So how would you like to proceed with this? Should I propose a new
>> >> patch somewhere?
>> >
>> > No problem, I'll apply this as-is.  But it doesn't apply to the
>> > 3.4-stable tree cleanly, can you send me a backported version if it's
>> > still needed there as well?
>> >
>>
>> Yes, the code was broken from the start. 3.4 version is attached, the
>> only difference is the missing ENDPROC() at the end of the asm file.
>
> Now applied, thanks.
>
>> In the mean time, Herbert has submitted a fix for the sparse warning,
>> but we settled on a different fix than I had suggested before.
>> https://git.kernel.org/cgit/linux/kernel/git/herbert/cryptodev-2.6.git/commit/?id=0ea481466d1c
>>
>> Note that this code has not been tested (not by me, at least), so I
>> wouldn't suggest you take it straight away, but if you care about the
>> sparse warning, we could add a cc stable to it as well, I suppose.
>
> If it's a real bugfix that people can hit, then yse, I'll take it.  Just
> let me know when it hits Linus's tree.
>

Hardly. The only thing it fixes is a diagnostic related to the use of
be128 where u128 is more appropriate,  only this time, it changes the
type throughout the file rather than using a __force cast when
accessing the variable, as I did in my original fix.

-- 
Ard.
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