linux-kernel - Re: Cryptomgr race vs built-in aesni

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Date:	Thu, 11 Aug 2011 12:40:06 -0400
From:	Josh Boyer <jwboyer@...hat.com>
To:	Herbert Xu <herbert@...dor.hengli.com.au>
Cc:	linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: Cryptomgr race vs built-in aesni

> Fedora has had a bug[1] open for a while with people seeing this upon boot:

> [    0.807387] alg: skcipher: Failed to load transform for ecb-aes-aesni: -2

> We're still seeing it with the 3.0 kernel, so I poked at it today.

<snip>

> So it seems that the aesni module is trying to register the ecb(aes) alg
> and before that completes (or something?) the test gets scheduled and
> tries to do a CRYPTO_MSG_ALG_REQUEST on something that hasn't
> finished it's module_init function yet.  Eventually the aesni_init function
> completes successfully (the last printk), so I'm assuming that the
> module is still present but that particular algorithm is listed as unavailable.

Ok, so it's not what I thought it was.  I did some more investigation today,
and it seems that the ablk_ebc_alg is missing the ivsize setting and the
crypto stack doesn't like that on a CRYPTO_ALG_TYPE_BLKCIPHER type.  I added
ivsize = AES_BLOCK_SIZE, and the error message goes away entirely.  This also
matches how ablk_cbc_alg works now, so I'm somewhat guessing this is correct.

My understanding of the crypto layer is at best non-existent, so if I'm wrong
please shout.  I'll send a patch sortly.

josh
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