From: Daniel Axtens <dja@axtens•net>
To: Eric Biggers <ebiggers@kernel•org>
Cc: leo.barbosa@canonical•com, nayna@linux•ibm.com,
Herbert Xu <herbert@gondor•apana.org.au>,
Stephan Mueller <smueller@chronox•de>,
Nayna <nayna@linux•vnet.ibm.com>,
omosnacek@gmail•com, marcelo.cerri@canonical•com,
pfsmorigo@gmail•com, linux-crypto@vger•kernel.org,
leitao@debian•org, George Wilson <gcwilson@linux•ibm.com>,
linuxppc-dev@lists•ozlabs.org
Subject: Re: [PATCH] crypto: vmx - fix copy-paste error in CTR mode
Date: Thu, 16 May 2019 15:28:48 +1000 [thread overview]
Message-ID: <87y337ynlb.fsf@dja-thinkpad.axtens.net> (raw)
In-Reply-To: <20190516025603.GB23200@sol.localdomain>
Eric Biggers <ebiggers@kernel•org> writes:
> On Thu, May 16, 2019 at 12:12:48PM +1000, Daniel Axtens wrote:
>>
>> I'm also seeing issues with ghash with the extended tests:
>>
>> [ 7.582926] alg: hash: p8_ghash test failed (wrong result) on test vector 0, cfg="random: use_final src_divs=[<reimport>9.72%@+39832, <reimport>18.2%@+65504, <reimport,nosimd>45.57%@alignmask+18, <reimport,nosimd>15.6%@+65496, 6.83%@+65514, <reimport,nosimd>1.2%@+25, <reim"
>>
>> It seems to happen when one of the source divisions has nosimd and the
>> final result uses the simd finaliser, so that's interesting.
>>
>
> The bug is that p8_ghash uses different shash_descs for the SIMD and no-SIMD
> cases. So if you start out doing the hash in SIMD context but then switch to
> no-SIMD context or vice versa, the digest will be wrong. Note that there can be
> an ->export() and ->import() in between, so it's not quite as obscure a case as
> one might think.
Ah cool, I was just in the process of figuring this out for myself -
always lovely to have my theory confirmed!
> To fix it I think you'll need to make p8_ghash use 'struct ghash_desc_ctx' just
> like ghash-generic so that the two code paths can share the same shash_desc.
> That's similar to what the various SHA hash algorithms do.
This is very helpful, thank you. I guess I will do that then.
Regards,
Daniel
>
> - Eric
next prev parent reply other threads:[~2019-05-16 5:30 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-15 2:09 [PATCH] crypto: vmx - fix copy-paste error in CTR mode Daniel Axtens
2019-03-15 2:24 ` Eric Biggers
2019-03-15 4:24 ` Daniel Axtens
2019-03-15 4:34 ` Eric Biggers
2019-03-15 5:23 ` Daniel Axtens
2019-04-10 7:02 ` Eric Biggers
2019-04-11 14:47 ` Daniel Axtens
2019-04-11 17:40 ` Nayna
2019-04-13 3:41 ` Michael Ellerman
2019-05-06 15:53 ` Eric Biggers
2019-05-13 0:59 ` Herbert Xu
2019-05-13 11:39 ` Michael Ellerman
2019-05-14 17:35 ` Daniel Axtens
2019-05-15 3:53 ` Herbert Xu
2019-05-15 6:36 ` Daniel Axtens
2019-05-16 2:12 ` Daniel Axtens
2019-05-16 2:56 ` Eric Biggers
2019-05-16 5:28 ` Daniel Axtens [this message]
2019-03-18 8:41 ` Michael Ellerman
2019-03-18 9:13 ` Ard Biesheuvel
2019-03-19 0:52 ` Michael Ellerman
2019-03-18 6:03 ` Michael Ellerman
2019-03-20 8:40 ` Ondrej Mosnáček
2019-03-22 13:04 ` Herbert Xu
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