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    SubjectRe: [bug] crypto/vmx/p8_ghash memory corruption in 4.8-rc7
    Wed, Sep 28, 2016 at 08:33:18PM +0800, Herbert Xu wrote:
    > On Wed, Sep 28, 2016 at 09:28:44AM -0300, Marcelo Cerri wrote:
    > >
    > > The big difference between p8_ghash and padlock_sha1 is that
    > > padlock_sha1 defines alg->statesize as sizeof(struct sha1_state), which
    > > is the descsize value used by sha1_generic. This probably works but
    > > it's also wrong because the padlock_sha1 driver does not ensures that
    > > sha1_generic is always used.
    >
    > It should work because all our SHA implementations use the same
    > export format. This is not necessarily the case for GHASH though.
    >
    > > So, one solution is to hardcode ghash-generic as the fallback algorithm
    > > and update the descsize direct in its shash_alg structure. There's only
    > > one problem with that. ghash-generic desc type (struct ghash_desc_ctx)
    > > is not available for vmx_crypto at compile type, the type is defined
    > > directly in crypto/ghash-generic.c. That's the reason I added a function
    > > to get the fallback desc size at runtime in the patch I wrote as a prove
    > > of concept.
    >
    > The problem with your patch is that there is no guarantee that
    > you will get the same algorithm every time you allocate a fallback.
    > Someone may have loaded a new module for example.
    >
    > So I think the safe approach is to stick with ghash-generic and
    > expose its state data structure in a header file.

    Since generic is the only posible fallback for ppc, I think that's a
    good solution. :)

    >
    > Thanks,
    > --
    > Email: Herbert Xu <herbert@gondor.apana.org.au>
    > Home Page: http://gondor.apana.org.au/~herbert/
    > PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
    >

    --
    Paulo Flabiano Smorigo
    IBM Linux Technology Center

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