linux-kernel - Re: [PATCH crypto -v4 2/2] AES-NI: Add support to Intel AES-NI instructions for x86

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Date:	Fri, 16 Jan 2009 14:26:39 +1100
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Huang Ying <ying.huang@...el.com>
Cc:	roel kluin <roel.kluin@...il.com>,
	Sebastian Siewior <linux-crypto@...breakpoint.cc>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>
Subject: Re: [PATCH crypto -v4 2/2] AES-NI: Add support to Intel AES-NI
	instructions for x86_64 platform

On Fri, Jan 16, 2009 at 10:37:02AM +0800, Huang Ying wrote:
>
> But after checking blkcipher_walk_done() in 2.6.28, If input argument
> err != 0 and walk->flags & BLKCIPHER_WALK_SLOW != 0, when
> blkcipher_walk_done() return non-zero, walk->nbytes != 0. So I think it
> is a little fragile to use walk->nbytes == 0 indicate error.

Right, that's a bug.  Although this case shouldn't occur unless
wer have a buggy algorithm (that's why it's a WARN_ON).  But as
we're handling it anyway, we should ensure that the result is sane.

crypt: blkcipher - Fix WARN_ON handling in walk_done

When we get left-over bits from a slow walk, it means that the
underlying cipher has gone troppo.  However, as we're handling
that case we should ensure that the caller terminates the walk.

This patch does this by setting walk->nbytes to zero.

Reported-by: Huang Ying <ying.huang@...el.com>
Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>

diff --git a/crypto/blkcipher.c b/crypto/blkcipher.c
index 4a7e65c..d70a41c 100644
--- a/crypto/blkcipher.c
+++ b/crypto/blkcipher.c
@@ -124,6 +124,7 @@ int blkcipher_walk_done(struct blkcipher_desc *desc,
 	scatterwalk_done(&walk->in, 0, nbytes);
 	scatterwalk_done(&walk->out, 1, nbytes);
 
+err:
 	walk->total = nbytes;
 	walk->nbytes = nbytes;
 
@@ -132,7 +133,6 @@ int blkcipher_walk_done(struct blkcipher_desc *desc,
 		return blkcipher_walk_next(desc, walk);
 	}
 
-err:
 	if (walk->iv != desc->info)
 		memcpy(desc->info, walk->iv, crypto_blkcipher_ivsize(tfm));
 	if (walk->buffer != walk->page)

Thanks,
-- 
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Email: Herbert Xu ~{PmV>HI~} <herbert@...dor.apana.org.au>
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