random: do not use batches when !crng_ready()

It's too hard to keep the batches synchronized, and pointless anyway,
since in !crng_ready(), we're updating the base_crng key really often,
where batching only hurts. So instead, if the crng isn't ready, just
call into get_random_bytes(). At this stage nothing is performance
critical anyhow.

Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

1 files changed, 11 insertions, 3 deletions

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 2d10942ba534..a9f887b92ba2 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -466,10 +466,8 @@ static void crng_pre_init_inject(const void *input, size_t len, bool account)
 
 	if (account) {
 		crng_init_cnt += min_t(size_t, len, CRNG_INIT_CNT_THRESH - crng_init_cnt);
-		if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) {
-			++base_crng.generation;
+		if (crng_init_cnt >= CRNG_INIT_CNT_THRESH)
 			crng_init = 1;
-		}
 	}
 
 	spin_unlock_irqrestore(&base_crng.lock, flags);
@@ -625,6 +623,11 @@ u64 get_random_u64(void)
 
 	warn_unseeded_randomness(&previous);
 
+	if  (!crng_ready()) {
+		_get_random_bytes(&ret, sizeof(ret));
+		return ret;
+	}
+
 	local_lock_irqsave(&batched_entropy_u64.lock, flags);
 	batch = raw_cpu_ptr(&batched_entropy_u64);
 
@@ -659,6 +662,11 @@ u32 get_random_u32(void)
 
 	warn_unseeded_randomness(&previous);
 
+	if  (!crng_ready()) {
+		_get_random_bytes(&ret, sizeof(ret));
+		return ret;
+	}
+
 	local_lock_irqsave(&batched_entropy_u32.lock, flags);
 	batch = raw_cpu_ptr(&batched_entropy_u32);