Unverified Commit a1304cba authored May 07, 2020 by Arnd Bergmann Committed by Mark Brown May 08, 2020

ASoC: cros_ec_codec: allocate shash_desc dynamically

The wov_hotword_model_put() function has multiple large variables on
its stack, the largest of which is the result of SHASH_DESC_ON_STACK().
In total, this exceeds the warning limit for 32-bit architectures:

sound/soc/codecs/cros_ec_codec.c:776:12: error: stack frame size of 1152 bytes in function 'wov_hotword_model_put' [-Werror,-Wframe-larger-than=]

The function already has a dynamic crypto_alloc_shash() allocation, so
using kmalloc() for the descriptor is correct as well and does not
introduce any additional failure scenarios. With this, the stack usage
of wov_hotword_model_put() gets reduced to 480 bytes in my test
configuration.

Fixes: b6bc07d4 ("ASoC: cros_ec_codec: support WoV")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Tzung-Bi Shih <tzungbi@google.com>
Link: https://lore.kernel.org/r/20200507213405.1869430-1-arnd@arndb.de

Signed-off-by: Mark Brown <broonie@kernel.org>

parent 2d6201ee

sound/soc/codecs/cros_ec_codec.c

+9 −8

Original line number	Diff line number	Diff line
		@@ -108,22 +108,23 @@ static int calculate_sha256(struct cros_ec_codec_priv *priv,
		uint8_t buf, uint32_t size, uint8_t digest)
		{
		struct crypto_shash *tfm;
		struct shash_desc *desc;

		tfm = crypto_alloc_shash("sha256", CRYPTO_ALG_TYPE_SHASH, 0);
		if (IS_ERR(tfm)) {
		dev_err(priv->dev, "can't alloc shash\n");
		return PTR_ERR(tfm);
		}

		{
		SHASH_DESC_ON_STACK(desc, tfm);

		desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(tfm), GFP_KERNEL);
		if (!desc) {
		crypto_free_shash(tfm);
		return -ENOMEM;
		}
		desc->tfm = tfm;

		crypto_shash_digest(desc, buf, size, digest);
		shash_desc_zero(desc);
		}

		kfree(desc);
		crypto_free_shash(tfm);

		#ifdef DEBUG

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