On Fri, Apr 26, 2013 at 09:44:17AM -0700, Tim Chen wrote:
>
> +     old_tfm = crct10dif_tfm;
> +     crc_t10dif_newalg = true;
> +     /* make sure new alg flag is turned on before starting to switch tfm */
> +     mb();
> +
> +     new_tfm = crypto_alloc_shash("crct10dif", 0, 0);
> +     if (IS_ERR(new_tfm))
> +             goto done;
> +
> +     if (old_tfm)
> +             if (crypto_tfm_alg_priority(&old_tfm->base) >=
> +                 crypto_tfm_alg_priority(&new_tfm->base)) {
> +                     crypto_free_shash(new_tfm);
> +                     goto done;
> +             }
> +     crct10dif_tfm = new_tfm;
> +     /* make sure update to tfm pointer is completed */
> +     mb();
> +     crypto_free_shash(old_tfm);

This is not safe at all.  You'd need to use something like RCU.

However, I think this is an overkill.  Initialising it once should
be enough.  If someone really wanted to change things at run-time,
they could always build this as a module and unload/reload it.

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