From: "Jason A. Donenfeld" Jason@zx2c4.com
commit 1754abb3e7583c570666fa1e1ee5b317e88c89a0 upstream.
Prior, the "input_pool_data" array needed no real initialization, and so it was easy to mark it with __latent_entropy to populate it during compile-time. In switching to using a hash function, this required us to specifically initialize it to some specific state, which means we dropped the __latent_entropy attribute. An unfortunate side effect was this meant the pool was no longer seeded using compile-time random data. In order to bring this back, we declare an array in rand_initialize() with __latent_entropy and call mix_pool_bytes() on that at init, which accomplishes the same thing as before. We make this __initconst, so that it doesn't take up space at runtime after init.
Fixes: 6e8ec2552c7d ("random: use computational hash for entropy extraction") Reviewed-by: Dominik Brodowski linux@dominikbrodowski.net Reviewed-by: Theodore Ts'o tytso@mit.edu Signed-off-by: Jason A. Donenfeld Jason@zx2c4.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/char/random.c | 5 +++++ 1 file changed, 5 insertions(+)
--- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -970,6 +970,11 @@ int __init rand_initialize(void) bool arch_init = true; unsigned long rv;
+#if defined(LATENT_ENTROPY_PLUGIN) + static const u8 compiletime_seed[BLAKE2S_BLOCK_SIZE] __initconst __latent_entropy; + _mix_pool_bytes(compiletime_seed, sizeof(compiletime_seed)); +#endif + for (i = 0; i < BLAKE2S_BLOCK_SIZE; i += sizeof(rv)) { if (!arch_get_random_seed_long_early(&rv) && !arch_get_random_long_early(&rv)) {