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

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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: da001fb651 ("crypto: atmel-i2c - add support for SHA204A random number generator")
Cc: <stable@vger.kernel.org>
Signed-off-by: Marek Behún <kabel@kernel.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Marek Behún
2025-04-22 11:57:18 +02:00
committed by Greg Kroah-Hartman
parent 28401a63c0
commit 64b816a6c4
1 changed files with 6 additions and 0 deletions
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6
drivers/crypto/atmel-sha204a.c
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@@ -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);