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From: Stephan Mueller <smueller@chronox.de>
To: Andy Lutomirski <luto@kernel.org>
Cc: linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org,
	Matt Mackall <mpm@selenic.com>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	Rusty Russell <rusty@rustcorp.com.au>, Jens Axboe <axboe@fb.com>,
	Matt Mullins <mmullins@mmlx.us>
Subject: Re: [PATCH resend 4.9] hw_random: Don't use a stack buffer in add_early_randomness()
Date: Mon, 17 Oct 2016 19:17:31 +0200	[thread overview]
Message-ID: <2711337.nAU4qxUyQs@tauon.atsec.com> (raw)
In-Reply-To: <4169224b6858d1cf149f1a73f8a03603fa19076d.1476638125.git.luto@kernel.org>

Am Montag, 17. Oktober 2016, 10:06:27 CEST schrieb Andy Lutomirski:

Hi Andy,

> diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
> index 9203f2d130c0..340f96e44642 100644
> --- a/drivers/char/hw_random/core.c
> +++ b/drivers/char/hw_random/core.c
> @@ -84,14 +84,14 @@ static size_t rng_buffer_size(void)
> 
>  static void add_early_randomness(struct hwrng *rng)
>  {
> -	unsigned char bytes[16];
>  	int bytes_read;
> +	size_t size = min_t(size_t, 16, rng_buffer_size());
> 
>  	mutex_lock(&reading_mutex);
> -	bytes_read = rng_get_data(rng, bytes, sizeof(bytes), 1);
> +	bytes_read = rng_get_data(rng, rng_buffer, size, 1);
>  	mutex_unlock(&reading_mutex);
>  	if (bytes_read > 0)
> -		add_device_randomness(bytes, bytes_read);
> +		add_device_randomness(rng_buffer, bytes_read);

Shouldn't there be a memset(0) of the rng_buffer at this point to avoid having 
such data lingering in memory?


Ciao
Stephan

  parent reply	other threads:[~2016-10-17 17:17 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-10-17 17:06 [PATCH resend 4.9] hw_random: Don't use a stack buffer in add_early_randomness() Andy Lutomirski
2016-10-16 21:19 ` [PATCH " Matt Mullins
2016-10-17 17:17 ` Stephan Mueller [this message]
2016-10-17 17:30   ` [PATCH resend " Andy Lutomirski
2016-10-17 18:36     ` Stephan Mueller
2016-10-17 21:03       ` Andy Lutomirski
2016-10-17 21:14         ` Stephan Mueller
2016-10-19  3:50 ` Herbert Xu
2017-02-04  3:47 ` Yisheng Xie
2017-02-04  4:34   ` Matt Mullins
2017-02-04 10:32     ` Yisheng Xie

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