From: Dominik Brodowski linux@dominikbrodowski.net
commit 7c2fe2b32bf76441ff5b7a425b384e5f75aa530a upstream.
crng_init is protected by primary_crng->lock, so keep holding that lock when incrementing crng_init from 0 to 1 in crng_fast_load(). The call to pr_notice() can wait until the lock is released; this code path cannot be reached twice, as crng_fast_load() aborts early if crng_init > 0.
Signed-off-by: Dominik Brodowski linux@dominikbrodowski.net Reviewed-by: Eric Biggers ebiggers@google.com 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, 3 insertions(+), 2 deletions(-)
--- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -647,12 +647,13 @@ static size_t crng_fast_load(const u8 *c p[crng_init_cnt % CHACHA20_KEY_SIZE] ^= *cp; cp++; crng_init_cnt++; len--; ret++; } - spin_unlock_irqrestore(&primary_crng.lock, flags); if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) { invalidate_batched_entropy(); crng_init = 1; - pr_notice("fast init done\n"); } + spin_unlock_irqrestore(&primary_crng.lock, flags); + if (crng_init == 1) + pr_notice("fast init done\n"); return ret; }