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From: Eric Biggers <ebiggers@kernel.org>
To: Nathan Huckleberry <nhuck@google.com>
Cc: Bruno Goncalves <bgoncalv@redhat.com>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	"David S. Miller" <davem@davemloft.net>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Ard Biesheuvel <ardb@kernel.org>,
	linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] crypto: x86/polyval - Fix crashes when keys are not 16-byte aligned
Date: Mon, 17 Oct 2022 16:02:29 -0700	[thread overview]
Message-ID: <Y03fBQPM7h7+cfGK@sol.localdomain> (raw)
In-Reply-To: <20221017222620.715153-1-nhuck@google.com>

On Mon, Oct 17, 2022 at 03:26:20PM -0700, Nathan Huckleberry wrote:
> The key_powers array is not guaranteed to be 16-byte aligned, so using
> movaps to operate on key_powers is not allowed.
> 
> Switch movaps to movups.
> 
> Fixes: 34f7f6c30112 ("crypto: x86/polyval - Add PCLMULQDQ accelerated implementation of POLYVAL")
> Reported-by: Bruno Goncalves <bgoncalv@redhat.com>
> Signed-off-by: Nathan Huckleberry <nhuck@google.com>
> ---
>  arch/x86/crypto/polyval-clmulni_asm.S | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/crypto/polyval-clmulni_asm.S b/arch/x86/crypto/polyval-clmulni_asm.S
> index a6ebe4e7dd2b..32b98cb53ddf 100644
> --- a/arch/x86/crypto/polyval-clmulni_asm.S
> +++ b/arch/x86/crypto/polyval-clmulni_asm.S
> @@ -234,7 +234,7 @@
>  
>  	movups (MSG), %xmm0
>  	pxor SUM, %xmm0
> -	movaps (KEY_POWERS), %xmm1
> +	movups (KEY_POWERS), %xmm1
>  	schoolbook1_noload
>  	dec BLOCKS_LEFT
>  	addq $16, MSG

I thought that crypto_tfm::__crt_ctx is guaranteed to be 16-byte aligned,
and that the x86 AES code relies on that property.

But now I see that actually the x86 AES code manually aligns the context.
See aes_ctx() in arch/x86/crypto/aesni-intel_glue.c.

Did you consider doing the same for polyval?

If you do prefer this way, it would be helpful to leave a comment for
schoolbook1_iteration that mentions that the unaligned access support of
vpclmulqdq is being relied on, i.e. pclmulqdq wouldn't work.

- Eric

  reply	other threads:[~2022-10-17 23:06 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-17 22:26 [PATCH] crypto: x86/polyval - Fix crashes when keys are not 16-byte aligned Nathan Huckleberry
2022-10-17 23:02 ` Eric Biggers [this message]
2022-10-17 23:38   ` Nathan Huckleberry
2022-10-18  0:12     ` Eric Biggers
2022-10-18  4:03       ` Herbert Xu
2022-10-18 21:56         ` [PATCH v2] " Nathan Huckleberry
2022-10-18 22:39           ` Eric Biggers
2022-10-18 23:04             ` [PATCH v3] " Nathan Huckleberry
2022-10-18 23:12               ` Eric Biggers
2022-10-19 12:13               ` Bruno Goncalves
2022-10-21 11:39               ` Herbert Xu

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