tjh.dev / kernel
Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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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>

authored by

Dominik Brodowski and committed by
Herbert Xu 6ff63044 26a03981

+1 -2
+1 -2
drivers/char/hw_random/core.c
··· 64 64 static void add_early_randomness(struct hwrng *rng) 65 65 { 66 66 int bytes_read; 67 - size_t size = min_t(size_t, 16, rng_buffer_size()); 68 67 69 68 mutex_lock(&reading_mutex); 70 - bytes_read = rng_get_data(rng, rng_buffer, size, 0); 69 + bytes_read = rng_get_data(rng, rng_buffer, 32, 0); 71 70 mutex_unlock(&reading_mutex); 72 71 if (bytes_read > 0) 73 72 add_device_randomness(rng_buffer, bytes_read);