From: Jason A. Donenfeld <Jason@zx2c4.com>
Date: Tue, 3 May 2022 12:14:32 +0000 (+0200)
Subject: random: do not use batches when !crng_ready()
X-Git-Tag: v5.18.1~27
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=f0cb03957175452e8dfc18f3f7d8dd2698553bd4;p=thirdparty%2Fkernel%2Fstable.git

random: do not use batches when !crng_ready()

commit cbe89e5a375a51bbb952929b93fa973416fea74e upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 5c69252a3bd8c..5e4e990bc1bf0 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -465,10 +465,8 @@ 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);
@@ -624,6 +622,11 @@ 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);
 
@@ -658,6 +661,11 @@ 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);