linux-kernel - Re: [PATCH v11 1/2] crypto: AF

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Message-ID: <20150126043218.GA20911@gondor.apana.org.au>
Date:	Mon, 26 Jan 2015 15:32:18 +1100
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Stephan Mueller <smueller@...onox.de>
Cc:	Daniel Borkmann <dborkman@...hat.com>,
	'Quentin Gouchet' <quentin.gouchet@...il.com>,
	'LKML' <linux-kernel@...r.kernel.org>,
	linux-crypto@...r.kernel.org, linux-api@...r.kernel.org,
	Neil Horman <nhorman@...driver.com>
Subject: Re: [PATCH v11 1/2] crypto: AF_ALG: add AEAD support

On Mon, Jan 26, 2015 at 05:26:33AM +0100, Stephan Mueller wrote:
> Am Montag, 26. Januar 2015, 10:55:50 schrieb Herbert Xu:
> 
> Hi Herbert,
> 
> > On Wed, Jan 21, 2015 at 02:19:17AM +0100, Stephan Mueller wrote:
> > > +		/* use the existing memory in an allocated page */
> > > +		if (ctx->merge) {
> > > +			sg = sgl->sg + sgl->cur - 1;
> > > +			len = min_t(unsigned long, len,
> > > +				    PAGE_SIZE - sg->offset - sg->length);
> > > +			err = memcpy_from_msg(page_address(sg_page(sg)) +
> > > +					      sg->offset + sg->length,
> > > +					      msg, len);
> > > +			if (err)
> > > +				goto unlock;
> > > +
> > > +			sg->length += len;
> > > +			ctx->merge = (sg->offset + sg->length) &
> > > +				     (PAGE_SIZE - 1);
> > > +
> > > +			ctx->used += len;
> > > +			copied += len;
> > > +			size -= len;
> > 
> > Need to add a continue here to recheck size != 0.
> 
> Why would that be needed?
> 
> When size is still != 0 (i.e. the existing buffer is completely filled, we 
> have still some remaining data), we fall through to the while loop that 
> generates a new buffer.

Because when size == 0 you should exit the loop.  IOW if the new
data is completely merged you should get out and not continue.

Cheers,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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