Commit 8006aff1 authored by Marek Behún's avatar Marek Behún Committed by Herbert Xu
Browse files

crypto: atmel-sha204a - Set hwrng quality to lowest possible 

According to the review by Bill Cox [1], the Atmel SHA204A random number
generator produces random numbers with very low entropy.

Set the lowest possible entropy for this chip just to be safe.

[1] https://www.metzdowd.com/pipermail/cryptography/2014-December/023858.html



Fixes: da001fb6 ("crypto: atmel-i2c - add support for SHA204A random number generator")
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarMarek Behún <kabel@kernel.org>
Acked-by: default avatarArd Biesheuvel <ardb@kernel.org>
Reviewed-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 002ba346

drivers/crypto/atmel-sha204a.c

+6 −0
Original line number Diff line number Diff line
@@ -163,6 +163,12 @@ static int atmel_sha204a_probe(struct i2c_client *client) 
	i2c_priv->hwrng.name = dev_name(&client->dev);

	i2c_priv->hwrng.read = atmel_sha204a_rng_read;



	/*

	 * According to review by Bill Cox [1], this HWRNG has very low entropy.

	 * [1] https://www.metzdowd.com/pipermail/cryptography/2014-December/023858.html

	 */

	i2c_priv->hwrng.quality = 1;



	ret = devm_hwrng_register(&client->dev, &i2c_priv->hwrng);

	if (ret)

		dev_warn(&client->dev, "failed to register RNG (%d)\n", ret);