From: "Jason A. Donenfeld" Jason@zx2c4.com
commit 12e45a2a6308105469968951e6d563e8f4fea187 upstream.
RDRAND and RDSEED can fail sometimes, which is fine. We currently initialize the RNG with 512 bits of RDRAND/RDSEED. We only need 256 bits of those to succeed in order to initialize the RNG. Instead of the current "all or nothing" approach, actually credit these contributions the amount that is actually contributed.
Reviewed-by: Dominik Brodowski linux@dominikbrodowski.net Signed-off-by: Jason A. Donenfeld Jason@zx2c4.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/char/random.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)
--- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -891,9 +891,8 @@ early_param("random.trust_bootloader", p */ int __init random_init(const char *command_line) { - size_t i; ktime_t now = ktime_get_real(); - bool arch_init = true; + unsigned int i, arch_bytes; unsigned long rv;
#if defined(LATENT_ENTROPY_PLUGIN) @@ -901,11 +900,12 @@ int __init random_init(const char *comma _mix_pool_bytes(compiletime_seed, sizeof(compiletime_seed)); #endif
- for (i = 0; i < BLAKE2S_BLOCK_SIZE; i += sizeof(rv)) { + for (i = 0, arch_bytes = BLAKE2S_BLOCK_SIZE; + i < BLAKE2S_BLOCK_SIZE; i += sizeof(rv)) { if (!arch_get_random_seed_long_early(&rv) && !arch_get_random_long_early(&rv)) { rv = random_get_entropy(); - arch_init = false; + arch_bytes -= sizeof(rv); } _mix_pool_bytes(&rv, sizeof(rv)); } @@ -916,8 +916,8 @@ int __init random_init(const char *comma
if (crng_ready()) crng_reseed(); - else if (arch_init && trust_cpu) - credit_init_bits(BLAKE2S_BLOCK_SIZE * 8); + else if (trust_cpu) + credit_init_bits(arch_bytes * 8);
return 0; }