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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Jann Horn <jannh@google.com>,
        Theodore Tso <tytso@mit.edu>, stable@kernel.org
Subject: [PATCH 4.16 166/196] random: crng_reseed() should lock the crng instance that it is modifying
Date:   Sun, 22 Apr 2018 15:53:06 +0200
Message-Id: <20180422135112.860567110@linuxfoundation.org>
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4.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Theodore Ts'o <tytso@mit.edu>

commit 0bb29a849a6433b72e249eea7695477b02056e94 upstream.

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

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

--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -905,7 +905,7 @@ 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) &&
@@ -915,7 +915,7 @@ 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();