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hwrng: core - read() callback must be called for size of 32 or more bytes

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According to <linux/hw_random.h>, the @max parameter of the ->read
callback "is a multiple of 4 and >= 32 bytes". That promise was not
kept by add_early_randomness(), which only asked for 16 bytes. As
rng_buffer_size() is at least 32, we can simply ask for 32 bytes.

Cc: Matt Mackall <mpm@selenic.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Dominik Brodowski 2022-01-24 21:29:47 +01:00 committed by Herbert Xu
parent 26a0398131
commit 6ff6304497
1 changed files with 1 additions and 2 deletions
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3
drivers/char/hw_random/core.c
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@ -64,10 +64,9 @@ static size_t rng_buffer_size(void)
static void add_early_randomness(struct hwrng *rng)
{
int bytes_read;
size_t size = min_t(size_t, 16, rng_buffer_size());
mutex_lock(&reading_mutex);
bytes_read = rng_get_data(rng, rng_buffer, size, 0);
bytes_read = rng_get_data(rng, rng_buffer, 32, 0);
mutex_unlock(&reading_mutex);
if (bytes_read > 0)
add_device_randomness(rng_buffer, bytes_read);