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From: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Ard Biesheuvel <ardb@kernel.org>,
	Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
	linux-sparse@vger.kernel.org
Subject: Re: [PATCH 5/5] crypto: arm/ghash - use variably sized key struct
Date: Fri, 10 Jul 2020 02:16:20 +0200	[thread overview]
Message-ID: <20200710001620.he3twpsil2wnl4vj@ltop.local> (raw)
In-Reply-To: <20200709120937.GA13332@gondor.apana.org.au>

On Thu, Jul 09, 2020 at 10:09:37PM +1000, Herbert Xu wrote:
> On Thu, Jul 09, 2020 at 11:51:10AM +0300, Ard Biesheuvel wrote:
> >
> > That looks like a sparse bug to me. Since when is it not allowed to
> > pass a non-const value as a const parameter?
> > 
> > I.e., you can pass a u64[] to a function that takes a u64 const *,
> > giving the caller the guarantee that their u64[] will not be modified
> > during the call, even if it is passed by reference.
> > 
> > Here, we are dealing with u64[][2], but the same reasoning holds. A
> > const u64[][2] formal parameter (or u64 const (*)[2] which comes down
> > to the same thing) does not require a const argument, it only tells
> > the caller that the array will be left untouched. This is why the
> > compiler is perfectly happy with this arrangement.
> 
> You're right.  Luc, here is the patch that triggers the bogus
> warning with sparse.

Thanks for the analysis and the bug report.
A fix is under way and should be upstreamed in a few days.

-- Luc 

      reply	other threads:[~2020-07-10  0:16 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20200629073925.127538-1-ardb@kernel.org>
     [not found] ` <20200629073925.127538-6-ardb@kernel.org>
     [not found]   ` <20200709082200.GA1892@gondor.apana.org.au>
     [not found]     ` <CAMj1kXE8HELm1j3jx-+mHrK3OjG6Rjp4jtP_QEYorRBnRxA+=w@mail.gmail.com>
2020-07-09 12:09       ` [PATCH 5/5] crypto: arm/ghash - use variably sized key struct Herbert Xu
2020-07-10  0:16         ` Luc Van Oostenryck [this message]

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