random: crng_reseed() should lock the crng instance that it is modifying

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>

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 4f82fe0..9d24f3c 100644 (file)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -836,7 +836,7 @@ static void crng_reseed(struct crng_state *crng, struct entropy_store *r)
                _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) &&
@@ -852,7 +852,7 @@ static void crng_reseed(struct crng_state *crng, struct entropy_store *r)
                wake_up_interruptible(&crng_init_wait);
                pr_notice("random: crng init done\n");
        }
-       spin_unlock_irqrestore(&primary_crng.lock, flags);
+       spin_unlock_irqrestore(&crng->lock, flags);
 }
 
 static inline void maybe_reseed_primary_crng(void)