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

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>

diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
index e860e04..c2d260b 100644 (file)
--- a/drivers/char/hw_random/core.c
+++ b/drivers/char/hw_random/core.c
@@ -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);