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Date:   Mon, 22 Mar 2021 13:13:26 +0100
From:   LABBE Corentin <clabbe@baylibre.com>
To:     Dan Carpenter <dan.carpenter@oracle.com>
Cc:     Eric Biggers <ebiggers@kernel.org>, linux-crypto@vger.kernel.org,
        Neil Horman <nhorman@tuxdriver.com>, stable@vger.kernel.org
Subject: Re: [PATCH] crypto: rng - fix crypto_rng_reset() refcounting when
 !CRYPTO_STATS
Message-ID: <YFiJ5hnKfXzlAtQi@Red>
References: <20210322050748.265604-1-ebiggers@kernel.org>
 <20210322054522.GC1667@kadam>
 <YFgyaeeY6k6Pltw7@sol.localdomain>
 <20210322073300.GF1667@kadam>
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Le Mon, Mar 22, 2021 at 10:33:01AM +0300, Dan Carpenter a ?crit :
> On Sun, Mar 21, 2021 at 11:00:09PM -0700, Eric Biggers wrote:
> > On Mon, Mar 22, 2021 at 08:45:22AM +0300, Dan Carpenter wrote:
> > > On Sun, Mar 21, 2021 at 10:07:48PM -0700, Eric Biggers wrote:
> > > > From: Eric Biggers <ebiggers@google.com>
> > > > 
> > > > crypto_stats_get() is a no-op when the kernel is compiled without
> > > > CONFIG_CRYPTO_STATS, so pairing it with crypto_alg_put() unconditionally
> > > > (as crypto_rng_reset() does) is wrong.
> > > > 
> > > 
> > > Presumably the intention was that _get() and _put() should always pair.
> > > It's really ugly and horrible that they don't. We could have
> > > predicted bug like this would happen and will continue to happen until
> > > the crypto_stats_get() is renamed.
> > > 
> > 
> > Well, the crypto stats stuff has always been pretty broken, so I don't think
> > people have looked at it too closely.  Currently crypto_stats_get() pairs with
> > one of the functions that tallies the statistics, such as
> > crypto_stats_rng_seed() or crypto_stats_aead_encrypt().  What change are you
> > suggesting, exactly?  Maybe moving the conditional crypto_alg_put() into a new
> > function crypto_stats_put() and moving it into the callers?  Or do you think the
> > functions should just be renamed to something like crypto_stats_begin() and
> > crypto_stats_end_{rng_seed,aead_encrypt}()?
> 
> To be honest, I misread the crypto_alg_put() thinking that it was
> crypto_*stats*_put().  My favourite fix would be to introduce a
> crypto_stats_put() which is a mirror of crypto_stats_get() and ifdeffed
> out if we don't have CONFIG_CRYPTO_STATS.
> 

I agree it will be better.
I can work on adding crypto_stats_put() if you want.

Regards