{
        struct ccp_ctx *ctx = crypto_tfm_ctx(crypto_ahash_tfm(tfm));
        struct crypto_shash *shash = ctx->u.sha.hmac_tfm;
-       struct {
-               struct shash_desc sdesc;
-               char ctx[crypto_shash_descsize(shash)];
-       } desc;
+
+       SHASH_DESC_ON_STACK(sdesc, shash);
+
        unsigned int block_size = crypto_shash_blocksize(shash);
        unsigned int digest_size = crypto_shash_digestsize(shash);
        int i, ret;
 
        if (key_len > block_size) {
                /* Must hash the input key */
-               desc.sdesc.tfm = shash;
-               desc.sdesc.flags = crypto_ahash_get_flags(tfm) &
+               sdesc->tfm = shash;
+               sdesc->flags = crypto_ahash_get_flags(tfm) &
                        CRYPTO_TFM_REQ_MAY_SLEEP;
 
-               ret = crypto_shash_digest(&desc.sdesc, key, key_len,
+               ret = crypto_shash_digest(sdesc, key, key_len,
                                          ctx->u.sha.key);
                if (ret) {
                        crypto_ahash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);