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Message-ID: <2711337.nAU4qxUyQs@tauon.atsec.com>
Date: Mon, 17 Oct 2016 19:17:31 +0200
From: Stephan Mueller <smueller@...onox.de>
To: Andy Lutomirski <luto@...nel.org>
Cc: linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
Matt Mackall <mpm@...enic.com>,
Herbert Xu <herbert@...dor.apana.org.au>,
Rusty Russell <rusty@...tcorp.com.au>,
Jens Axboe <axboe@...com>, Matt Mullins <mmullins@...x.us>
Subject: Re: [PATCH resend 4.9] hw_random: Don't use a stack buffer in add_early_randomness()
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
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