From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5C53C2BCF7E for ; Tue, 29 Apr 2025 10:19:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745921989; cv=none; b=F+v7ch/dtjkYU7AwsA3/R4zzDeQE0UGrh0PQwXuyqx0rnBhkxTpItZZa30NeE8Dnrlo7suIe7bf8k5GC5uzNT7YVDNtWfTmRbhesfkMhlj1dER7kBLeNU9ncIn0hd6/81FElAy10vcAcQbpPVNAQmCGFFYdeZN/F+F8xqQjUpT0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745921989; c=relaxed/simple; bh=ZnnR1opHoeqkU7NnaS4z2CSMYREwbdUIkemIpT+1vCg=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:Content-Type; b=t9IX2Mk5dBe6qEsxSy3+BfKqaLfstqyr3r5c6iNjhvvGvAxKX7t4SUR4JjR5Xl0ask65uOxsXE5sKV852s/45Z/B3vw0bHDCGL71PCixWBedyu+pPCaVe2hVgITMLNJbq9SGocBHOOPPbxpjLwBObKAAL8kO1wWLauTDwepws08= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=YwRz7e0P; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="YwRz7e0P" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5084FC4CEE3; Tue, 29 Apr 2025 10:19:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1745921988; bh=ZnnR1opHoeqkU7NnaS4z2CSMYREwbdUIkemIpT+1vCg=; h=From:To:Cc:Subject:Date:From; b=YwRz7e0PIqX1W96dxIF6Y57Xo2wsATvfIHmA6PpCCHPQf/2zj5ZCoQkg1RlChuZwE YFWEjcyc5F7XpoUzKX4JTin7OevLvdxIg9YGLUqdiQTWii4ZwW4tnb2UPxFdslnPZr sTPm5twL+ogAEk2BplLFqmgemNBThoHd2GyaUj0cayezMHyvHvFFD7O4+9ni4V48xQ 6TB00QhoxNqp+M657lyxoRT+0gaPa1Jqt0S0wnjaQ284iCtiOHc/Mf3bFYNyA2xq64 k6qao8nyBoMEuLtxzlxoS20ERAr/ghp2cKKqU+Sey0C6sHQrxxA6w904bVh/OfQT2J xU/KJRNoFfNYQ== From: =?UTF-8?q?Marek=20Beh=C3=BAn?= To: gregkh@linuxfoundation.org, stable@vger.kernel.org, Sasha Levin Cc: ardb@kernel.org, herbert@gondor.apana.org.au, linus.walleij@linaro.org Subject: [PATCH 6.1.y] crypto: atmel-sha204a - Set hwrng quality to lowest possible Date: Tue, 29 Apr 2025 12:19:44 +0200 Message-ID: <20250429101944.19440-1-kabel@kernel.org> X-Mailer: git-send-email 2.49.0 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 [ rebased for 6.1 ] Signed-off-by: Marek Behún --- drivers/crypto/atmel-sha204a.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/crypto/atmel-sha204a.c b/drivers/crypto/atmel-sha204a.c index a84b657598c6..51738c730717 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) -- 2.49.0