linux-kernel - Re: algif_hash: splice of data

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Message-ID: <5492C6FC.50005@c-s.fr>
Date:	Thu, 18 Dec 2014 13:22:20 +0100
From:	leroy christophe <christophe.leroy@....fr>
To:	Stephan Mueller <smueller@...onox.de>,
	Herbert Xu <herbert@...dor.apana.org.au>
CC:	linux-crypto <linux-crypto@...r.kernel.org>,
	'LKML' <linux-kernel@...r.kernel.org>
Subject: Re: algif_hash: splice of data > 2**16

Le 18/12/2014 13:15, Stephan Mueller a écrit :
> Hi Herbert,
>
> While testing the vmsplice/splice interface of algif_hash I was made
> aware of the problem that data blobs larger than 16 pages do not seem to
> be hashed properly.
>
> For testing, a file is mmap()ed and handed to vmsplice / splice. If the
> file is smaller than 2**16, the interface returns the proper hash.
> However, when the file is larger, only the first 2**16 bytes seem to be
> used.
>
> When adding printk's to hash_sendpage, I see that this function is
> invoked exactly 16 times where the first 15 invocations have the
> MSG_MORE flag set and the last invocation does not have MSG_MORE.
>
>
Hi Stephan,

I have already noticed the same issue and proposed a patch, but I never 
got any feedback and it has never been merged, allthought I pinged it a 
few times.

See https://lkml.org/lkml/2014/4/18/276

Christophe
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