From: Dominik Brodowski linux@dominikbrodowski.net
commit 7191c628fe07b70d3f37de736d173d1b115396ed upstream.
crng_init is protected by primary_crng->lock. Therefore, we need to hold this lock when increasing crng_init to 2. As we shouldn't hold this lock for too long, only hold it for those parts which require protection.
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 | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
--- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -500,6 +500,7 @@ static void crng_reseed(void) int entropy_count; unsigned long next_gen; u8 key[CHACHA_KEY_SIZE]; + bool finalize_init = false;
/* * First we make sure we have POOL_MIN_BITS of entropy in the pool, @@ -527,12 +528,14 @@ static void crng_reseed(void) ++next_gen; WRITE_ONCE(base_crng.generation, next_gen); WRITE_ONCE(base_crng.birth, jiffies); - spin_unlock_irqrestore(&base_crng.lock, flags); - memzero_explicit(key, sizeof(key)); - if (crng_init < 2) { invalidate_batched_entropy(); crng_init = 2; + finalize_init = true; + } + spin_unlock_irqrestore(&base_crng.lock, flags); + memzero_explicit(key, sizeof(key)); + if (finalize_init) { process_random_ready_list(); wake_up_interruptible(&crng_init_wait); kill_fasync(&fasync, SIGIO, POLL_IN);