Linux cryptographic layer development
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From: Tudor Ambarus <tudor.ambarus@microchip.com>
To: Romain Izard <romain.izard.pro@gmail.com>,
	<linux-crypto@vger.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Cc: Cyrille Pitchen <cyrille.pitchen@atmel.com>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	"David S. Miller" <davem@davemloft.net>,
	Nicolas Ferre <nicolas.ferre@microchip.com>
Subject: Re: Kernel panic when using ccm(aes) with the Atmel AES HW accelerator
Date: Mon, 23 Oct 2017 15:38:59 +0300	[thread overview]
Message-ID: <39a43561-e0e6-a3b7-e2c0-bd7e6bf1be47@microchip.com> (raw)
In-Reply-To: <CAGkQfmP6Kq4DEBbGU7AW71PjbUJ2acdJF5PVDm6VqZkUaaoEzA@mail.gmail.com>

Hi, Romain,

On 10/18/2017 04:32 PM, Romain Izard wrote:
> my fix also led to a
> systematic oops when running the ccm(aes) test case.

The NULL deference appears because of a memory corruption issue.

atmel-aes does not implement ccm(aes), so the algorithm will be in the
following form: ccm_base(atmel-ctr-aes,cbcmac(aes-generic)).

ccm auth uses the first byte of the IV as length and eventually will
memset memory to zero based on that length (see set_msg_len()). CTR
overwrites the iv with the last ciphertext block and the length will be
wrong.

I will propose a fix, but I'm taking my time to better understand why
CTR requires to overwrite the iv with the last ciphertext block.

Cheers,
ta

  reply	other threads:[~2017-10-23 12:39 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-18 13:32 Kernel panic when using ccm(aes) with the Atmel AES HW accelerator Romain Izard
2017-10-23 12:38 ` Tudor Ambarus [this message]
2017-10-24  3:20   ` Herbert Xu
2017-10-24  9:30     ` Romain Izard
2017-10-24 15:25 ` Tudor Ambarus
2017-10-26 12:34 ` Tudor Ambarus
2017-10-27 12:02   ` Romain Izard

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