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SubjectRe: [PATCH 1/1] crypto: testmgr - call shash_init in crc32c algo
Hi Lionel,

On Mon, Apr 01, 2019 at 02:54:24PM +0200, Lionel Debieve wrote:
> In case of device call required in low level driver,
> the context must be initialized before calling the final
> function.
>
> Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
> ---
> crypto/testmgr.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/crypto/testmgr.c b/crypto/testmgr.c
> index 8386038..4a00d7c 100644
> --- a/crypto/testmgr.c
> +++ b/crypto/testmgr.c
> @@ -2181,6 +2181,13 @@ static int alg_test_crc32c(const struct alg_test_desc *desc,
> shash->tfm = tfm;
> shash->flags = 0;
>
> + err = crypto_shash_init(shash);
> + if (err) {
> + printk(KERN_ERR "alg: crc32c: init failed for "
> + "%s: %d\n", driver, err);
> + break;
> + }
> +
> *ctx = 420553207;
> err = crypto_shash_final(shash, (u8 *)&val);
> if (err) {
> --
> 2.7.4
>

This defeats the point of the test, which is that crc32c implementations are
expected to use the same shash_desc context format and be usable by calling
crypto_shash_update() directly after initializing the context manually, without
a prior crypto_shash_init(). See for example ext4_chksum() in fs/ext4/ext4.h:

static inline u32 ext4_chksum(struct ext4_sb_info *sbi, u32 crc,
const void *address, unsigned int length)
{
struct {
struct shash_desc shash;
char ctx[4];
} desc;

BUG_ON(crypto_shash_descsize(sbi->s_chksum_driver)!=sizeof(desc.ctx));

desc.shash.tfm = sbi->s_chksum_driver;
desc.shash.flags = 0;
*(u32 *)desc.ctx = crc;

BUG_ON(crypto_shash_update(&desc.shash, address, length));

return *(u32 *)desc.ctx;
}

I think you need to fix the stm32 crc32 driver to not store anything extra in
the shash_desc context, and only use hardware during ->update().

- Eric

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