linux-kernel - Re: [RFC v3] crypto: ccree - protect against short scatterlists

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Date:   Tue, 28 Jan 2020 11:30:54 +0200
From:   Gilad Ben-Yossef <gilad@...yossef.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Eric Biggers <ebiggers@...nel.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        Ofir Drang <ofir.drang@....com>,
        Linux Crypto Mailing List <linux-crypto@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [RFC v3] crypto: ccree - protect against short scatterlists

On Tue, Jan 28, 2020 at 10:30 AM Geert Uytterhoeven
<geert@...ux-m68k.org> wrote:
>
> Hi Eric,
>
> On Tue, Jan 28, 2020 at 4:01 AM Eric Biggers <ebiggers@...nel.org> wrote:
> > On Mon, Jan 27, 2020 at 04:22:53PM +0100, Geert Uytterhoeven wrote:
> > > On Mon, Jan 27, 2020 at 4:08 PM Gilad Ben-Yossef <gilad@...yossef.com> wrote:
> > > > Deal gracefully with the event of being handed a scatterlist
> > > > which is shorter than expected.
> > > >
> > > > This mitigates a crash in some cases due to
> > > > attempt to map empty (but not NULL) scatterlists with none
> > > > zero lengths.
> > > >
> > > > Signed-off-by: Gilad Ben-Yossef <gilad@...yossef.com>
> > > > Reported-by: Geert Uytterhoeven <geert@...ux-m68k.org>
> > >
> > > Thank you, boots fine on Salvator-XS with R-Car H3ES2.0, and
> > > CONFIG_CRYPTO_MANAGER_DISABLE_TESTS=y.
> > >
> > > Tested-by: Geert Uytterhoeven <geert+renesas@...der.be>
> >
> > Note that you need to *unset* CONFIG_CRYPTO_MANAGER_DISABLE_TESTS to enable the
> > self-tests.
>
> Sorry, that's what I meant (too used to type "=y" to enable something ;-)
>
> > So to run the full tests, the following is needed:
> >
> > # CONFIG_CRYPTO_MANAGER_DISABLE_TESTS is not set
>
> With just this, it no longer crashes.
>
> > CONFIG_CRYPTO_MANAGER_EXTRA_TESTS=y
>
> With the extra tests enabled, it still crashes :-(
>

That's fine - this is the second issue I was talking about.
The patch I sent before was not really a fix - more a stop gap
designed to see if I understand the issue you are seeing.

I will send out a patch fixing the root cause of both and this should
resolve both issues.
I just want to run it through some internal tests to make sure it did
not break something else first.

Thanks!
Gilad