Re: [RFC PATCH 1/2] net: wireless: Add Nordic nRF70 series Wi-Fi driver

[Eric Biggers <ebiggers@kernel.org>]

On Mon, Mar 24, 2025 at 10:10:44PM +0100, Artur Rojek wrote:
> +static int nrf70_verify_firmware(struct device *dev,
> +				 const struct nrf70_fw_header *fw)
> +{
> +	struct crypto_shash *alg;
> +	u8 hash[NRF70_FW_HASH_LEN];
> +	int ret;
> +
> +	alg = crypto_alloc_shash("sha256", 0, 0);
> +	if (IS_ERR(alg)) {
> +		ret = PTR_ERR(alg);
> +		dev_err(dev, "Unable to allocate shash memory: %d\n", ret);
> +		goto out;
> +	};
> +
> +	if (crypto_shash_digestsize(alg) != NRF70_FW_HASH_LEN) {
> +		dev_err(dev, "Incorrect digest size\n");
> +		ret = -EFAULT;
> +		goto out;
> +	}
> +
> +	ret = crypto_shash_tfm_digest(alg, fw->data, fw->length, hash);
> +	if (ret) {
> +		dev_err(dev, "Unable to compute hash\n");
> +		goto out;
> +	}
> +
> +	if (memcmp(fw->hash, hash, sizeof(hash))) {
> +		dev_err(dev, "Invalid firmware checksum\n");
> +		ret = -EFAULT;
> +	}
> +
> +out:
> +	crypto_free_shash(alg);
> +
> +	return ret;
> +}

You can just use sha256() here (and select CRYPTO_LIB_SHA256 from your kconfig
option).  It's much simpler than crypto_shash.

- Eric