From: Marek Behún Date: Tue, 22 Apr 2025 09:57:18 +0000 (+0200) Subject: crypto: atmel-sha204a - Set hwrng quality to lowest possible X-Git-Tag: v5.10.237~8 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=3c83be2bb574d1850a03605d45c9ae2e37e52478;p=thirdparty%2Fkernel%2Fstable.git crypto: atmel-sha204a - Set hwrng quality to lowest possible commit 8006aff15516a170640239c5a8e6696c0ba18d8e upstream. 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: da001fb651b00e1d ("crypto: atmel-i2c - add support for SHA204A random number generator") Cc: Signed-off-by: Marek Behún Acked-by: Ard Biesheuvel Reviewed-by: Linus Walleij Signed-off-by: Herbert Xu Signed-off-by: Greg Kroah-Hartman Signed-off-by: Marek Behún --- diff --git a/drivers/crypto/atmel-sha204a.c b/drivers/crypto/atmel-sha204a.c index c96c14e7dab1c..0ef92109ce22a 100644 --- a/drivers/crypto/atmel-sha204a.c +++ b/drivers/crypto/atmel-sha204a.c @@ -107,7 +107,12 @@ 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; - i2c_priv->hwrng.quality = 1024; + + /* + * 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)