From 0bb29a849a6433b72e249eea7695477b02056e94 Mon Sep 17 00:00:00 2001
From: Theodore Ts'o <tytso@mit.edu>
Date: Thu, 12 Apr 2018 00:50:45 -0400
Subject: [PATCH] random: crng_reseed() should lock the crng instance that it is modifying
Git-commit: 0bb29a849a6433b72e249eea7695477b02056e94
Patch-mainline: v4.17-rc2
References: bsc#1051510

Reported-by: Jann Horn <jannh@google.com>
Fixes: 1e7f583af67b ("random: make /dev/urandom scalable for silly...")
Cc: stable@kernel.org # 4.8+
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jann Horn <jannh@google.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/char/random.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -906,7 +906,7 @@ static void crng_reseed(struct crng_stat
 		_crng_backtrack_protect(&primary_crng, buf.block,
 					CHACHA20_KEY_SIZE);
 	}
-	spin_lock_irqsave(&primary_crng.lock, flags);
+	spin_lock_irqsave(&crng->lock, flags);
 	for (i = 0; i < 8; i++) {
 		unsigned long	rv;
 		if (!arch_get_random_seed_long(&rv) &&
@@ -916,7 +916,7 @@ static void crng_reseed(struct crng_stat
 	}
 	memzero_explicit(&buf, sizeof(buf));
 	crng->init_time = jiffies;
-	spin_unlock_irqrestore(&primary_crng.lock, flags);
+	spin_unlock_irqrestore(&crng->lock, flags);
 	if (crng == &primary_crng && crng_init < 2) {
 		invalidate_batched_entropy();
 		numa_crng_init();