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Date: Sat, 24 Feb 2024 08:52:34 +0800
From: Herbert Xu <herbert@gondor.apana.org.au>
To: Ard Biesheuvel <ardb+git@google.com>
Cc: linux-crypto@vger.kernel.org, Ard Biesheuvel <ardb@kernel.org>,
	syzbot+f1ceaa1a09ab891e1934@syzkaller.appspotmail.com,
	Eric Biggers <ebiggers@google.com>
Subject: Re: [PATCH v2] crypto: arm64/neonbs - fix out-of-bounds access on
 short input
Message-ID: <Zdk90hKLkPcb2NcD@gondor.apana.org.au>
References: <20240223132035.3174952-1-ardb+git@google.com>
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On Fri, Feb 23, 2024 at 02:20:35PM +0100, Ard Biesheuvel wrote:
> From: Ard Biesheuvel <ardb@kernel.org>
> 
> The bit-sliced implementation of AES-CTR operates on blocks of 128
> bytes, and will fall back to the plain NEON version for tail blocks or
> inputs that are shorter than 128 bytes to begin with.
> 
> It will call straight into the plain NEON asm helper, which performs all
> memory accesses in granules of 16 bytes (the size of a NEON register).
> For this reason, the associated plain NEON glue code will copy inputs
> shorter than 16 bytes into a temporary buffer, given that this is a rare
> occurrence and it is not worth the effort to work around this in the asm
> code.
> 
> The fallback from the bit-sliced NEON version fails to take this into
> account, potentially resulting in out-of-bounds accesses. So clone the
> same workaround, and use a temp buffer for short in/outputs.
> 
> Fixes: fc074e130051 ("crypto: arm64/aes-neonbs-ctr - fallback to plain NEON for final chunk")
> Reported-by: syzbot+f1ceaa1a09ab891e1934@syzkaller.appspotmail.com
> Reviewed-by: Eric Biggers <ebiggers@google.com>
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
> ---
>  arch/arm64/crypto/aes-neonbs-glue.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)

Patch applied.  Thanks.
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
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