linux-kernel - Re: [PATCH] crypto: arm64/aes - do not call crypto_unregister

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Message-ID: <20171124055233.GA16381@Red>
Date:   Fri, 24 Nov 2017 06:52:33 +0100
From:   LABBE Corentin <clabbe@...libre.com>
To:     Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc:     Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] crypto: arm64/aes - do not call
 crypto_unregister_skcipher twice on error

On Wed, Nov 22, 2017 at 08:55:14AM +0000, Ard Biesheuvel wrote:
> Hello Corentin,
> 
> On 22 November 2017 at 08:08, Corentin Labbe <clabbe@...libre.com> wrote:
> > When a cipher fail
> 
> fails
> 
> > to register in aes_init(), the error path go thought
> 
> goes through
> 
> > aes_exit() then crypto_unregister_skciphers().
> > Since aes_exit calls also crypto_unregister_skcipher, this trigger a
> 
> triggers
> 
> > refcount_t: underflow; use-after-free.
> >
> > Signed-off-by: Corentin Labbe <clabbe@...libre.com>
> > ---
> >  arch/arm64/crypto/aes-glue.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/arm64/crypto/aes-glue.c b/arch/arm64/crypto/aes-glue.c
> > index 998ba519a026..9e42ec96243e 100644
> > --- a/arch/arm64/crypto/aes-glue.c
> > +++ b/arch/arm64/crypto/aes-glue.c
> > @@ -664,7 +664,10 @@ static int __init aes_init(void)
> >         return 0;
> >
> >  unregister_simds:
> > -       aes_exit();
> > +       for (i = 0; i < ARRAY_SIZE(aes_simd_algs); i++)
> > +               if (aes_simd_algs[i])
> > +                       simd_skcipher_free(aes_simd_algs[i]);
> > +       crypto_unregister_shashes(mac_algs, ARRAY_SIZE(mac_algs));
> >  unregister_ciphers:
> >         crypto_unregister_skciphers(aes_algs, ARRAY_SIZE(aes_algs));
> >         return err;
> > --
> > 2.13.6
> >
> >
> 
> 
> Would this also fix it?
> 
> diff --git a/arch/arm64/crypto/aes-glue.c b/arch/arm64/crypto/aes-glue.c
> index 998ba519a026..2fa850e86aa8 100644
> --- a/arch/arm64/crypto/aes-glue.c
> +++ b/arch/arm64/crypto/aes-glue.c
> @@ -665,6 +665,7 @@ static int __init aes_init(void)
> 
>  unregister_simds:
>         aes_exit();
> +       return err;
>  unregister_ciphers:
>         crypto_unregister_skciphers(aes_algs, ARRAY_SIZE(aes_algs));
>         return err;

Yes it is better.

I will send a v2 today.

Regards