netdev - Re: Crypto oops in async_chainiv_do

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Message-ID: <20090831220459.GA15713@gondor.apana.org.au>
Date:	Tue, 1 Sep 2009 08:04:59 +1000
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Brad Bosch <bradbosch@...cast.net>
Cc:	linux-crypto@...r.kernel.org, netdev@...r.kernel.org,
	offbase0@...il.com
Subject: Re: Crypto oops in async_chainiv_do_postponed

On Mon, Aug 31, 2009 at 11:11:42AM -0500, Brad Bosch wrote:
>
> OK.  I was looking for something subtle because the crash takes a long
> time to happen.  But do you agree that the race I described above also
> a real bug?

No I don't think it is.  CHAINV_STATE_INUSE guarantees that only
one entity can use ctx->err at any time.

> Yes, I see that this bug must be the bug we would likely encounter first.
> Apparently, async_chainiv_do_postponed was never tested?  But I don't
> see how the patch you proposed below helps.  We still don't seem to be
> returning NULL from skcipher_dequeue_givcrypt when we reach the end of
> the queue because __crypto_dequeue_request is not checking for NULL
> before it subtracts offset.

Where we subtract the offset the pointer can never be NULL.  Please
try my patch.

Thanks,
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