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From:   Gilad Ben-Yossef <gilad@benyossef.com>
Date:   Mon, 28 Feb 2022 11:09:05 +0200
Message-ID: <CAOtvUMdX2N9XcBV81rSKz=orZ-3XHWW8ChXnuKAeiAsQy5P_Vg@mail.gmail.com>
Subject: Re: [PATCH] crypto: drbg: fix crypto api abuse
To:     Eric Biggers <ebiggers@kernel.org>
Cc:     Herbert Xu <herbert@gondor.apana.org.au>,
        "David S. Miller" <davem@davemloft.net>,
        Ofir Drang <ofir.drang@arm.com>,
        Corentin Labbe <clabbe.montjoie@gmail.com>,
        stable <stable@vger.kernel.org>,
        Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
        Linux kernel mailing list <linux-kernel@vger.kernel.org>
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Hi,

On Sun, Feb 27, 2022 at 12:12 PM Gilad Ben-Yossef <gilad@benyossef.com> wro=
te:
...


>
> I think the right thing to do right now is to verify that we indeed
> have a general issue and not something specific to one singular
> platform
> So the question becomes - do indeed the DMA api forbits aliased
> mappings and if so, under what conditions?
>
> Any ideas on how to check this?

OK, I've looked into this further and I think I was wrong.
The DMA api doesn't like overlapping writable mappings, but it seems
an overlapping read-only and writable mapping are fine.
If so I can indeed resolve this in the driver code by better
specifying DMA direction. Let me give this a go and let's drop this
patch in the meantime.

Thank you and sorry for the noise.

Gilad

--=20
Gilad Ben-Yossef
Chief Coffee Drinker

values of =CE=B2 will give rise to dom!