static int cbcmac_create(struct crypto_template *tmpl, struct rtattr **tb)
{
	struct shash_instance *inst;
	struct crypto_alg *alg;
	int err;

	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH);
	if (err)
		return err;

	alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
				  CRYPTO_ALG_TYPE_MASK);
	if (IS_ERR(alg))
		return PTR_ERR(alg);

	inst = shash_alloc_instance("cbcmac", alg);
	err = PTR_ERR(inst);
	if (IS_ERR(inst))
		goto out_put_alg;

	err = crypto_init_spawn(shash_instance_ctx(inst), alg,
				shash_crypto_instance(inst),
				CRYPTO_ALG_TYPE_MASK);
	if (err)
		goto out_free_inst;

	inst->alg.base.cra_priority = alg->cra_priority;
	inst->alg.base.cra_blocksize = 1;

	inst->alg.digestsize = alg->cra_blocksize;
	inst->alg.descsize = ALIGN(sizeof(struct cbcmac_desc_ctx),
				   alg->cra_alignmask + 1) +
			     alg->cra_blocksize;

	inst->alg.base.cra_ctxsize = sizeof(struct cbcmac_tfm_ctx);
	inst->alg.base.cra_init = cbcmac_init_tfm;
	inst->alg.base.cra_exit = cbcmac_exit_tfm;

	inst->alg.init = crypto_cbcmac_digest_init;
	inst->alg.update = crypto_cbcmac_digest_update;
	inst->alg.final = crypto_cbcmac_digest_final;
	inst->alg.setkey = crypto_cbcmac_digest_setkey;

	err = shash_register_instance(tmpl, inst);

out_free_inst:
	if (err)
		shash_free_instance(shash_crypto_instance(inst));

out_put_alg:
	crypto_mod_put(alg);
	return err;
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.