On Fri, Jun 04, 2021 at 09:00:09PM +0200, Ard Biesheuvel wrote:
> crypto_shash_alg_has_setkey() is implemented by testing whether the
> .setkey() member of a struct shash_alg points to the default version
> called shash_no_setkey(). As crypto_shash_alg_has_setkey() is a static
> inline, this requires shash_no_setkey() to be exported to modules.
>
> Unfortunately, when building with CFI, function pointers are routed
> via CFI stubs which are private to each module (or to the kernel proper)
> and so this function pointer comparison may fail spuriously.
>
> Let's fix this by turning crypto_shash_alg_has_setkey() into an out of
> line function, which makes the problem go away.
>
> Cc: Sami Tolvanen <samitolvanen@xxxxxxxxxx>
> Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
> ---
> crypto/shash.c | 11 ++++++++---
> include/crypto/internal/hash.h | 8 +-------
> 2 files changed, 9 insertions(+), 10 deletions(-)
I think this deserves a comment in the code.
> +bool crypto_shash_alg_has_setkey(struct shash_alg *alg)
> +{
> + return alg->setkey != shash_no_setkey;
> +}
> +EXPORT_SYMBOL_GPL(crypto_shash_alg_has_setkey);
This would be a good spot for the comment so someone doesn't try
to make it inline again later.
Thanks,
--
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
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