From 86ab60616ec6827b98b0f2c6ee96fcca77c018e2 Mon Sep 17 00:00:00 2001
From: Dominik Brodowski <linux@dominikbrodowski.net>
Date: Wed, 9 Feb 2022 19:57:06 +0100
Subject: [PATCH] random: fix locking for crng_init in crng_reseed()
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(-)
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 6108403564079..1da8687610ea6 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -502,6 +502,7 @@ 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,
@@ -529,12 +530,14 @@ 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);
--
2.30.2