From: Vladislav Efanov VEfanov@ispras.ru
commit abac3ac97fe8734b620e7322a116450d7f90aa43 upstream.
Syzkaller got a lot of crashes like: KASAN: use-after-free Write in *_timers*
All of these crashes point to the same memory area:
The buggy address belongs to the object at ffff88801f870000 which belongs to the cache kmalloc-8k of size 8192 The buggy address is located 5320 bytes inside of 8192-byte region [ffff88801f870000, ffff88801f872000)
This area belongs to : batadv_priv->batadv_priv_dat->delayed_work->timer_list
The reason for these issues is the lack of synchronization. Delayed work (batadv_dat_purge) schedules new timer/work while the device is being deleted. As the result new timer/delayed work is set after cancel_delayed_work_sync() was called. So after the device is freed the timer list contains pointer to already freed memory.
Found by Linux Verification Center (linuxtesting.org) with syzkaller.
Cc: stable@kernel.org Fixes: 2f1dfbe18507 ("batman-adv: Distributed ARP Table - implement local storage") Signed-off-by: Vladislav Efanov VEfanov@ispras.ru Acked-by: Sven Eckelmann sven@narfation.org Signed-off-by: Simon Wunderlich sw@simonwunderlich.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/batman-adv/distributed-arp-table.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/net/batman-adv/distributed-arp-table.c +++ b/net/batman-adv/distributed-arp-table.c @@ -68,7 +68,6 @@ static void batadv_dat_purge(struct work */ static void batadv_dat_start_timer(struct batadv_priv *bat_priv) { - INIT_DELAYED_WORK(&bat_priv->dat.work, batadv_dat_purge); queue_delayed_work(batadv_event_workqueue, &bat_priv->dat.work, msecs_to_jiffies(10000)); } @@ -783,6 +782,7 @@ int batadv_dat_init(struct batadv_priv * if (!bat_priv->dat.hash) return -ENOMEM;
+ INIT_DELAYED_WORK(&bat_priv->dat.work, batadv_dat_purge); batadv_dat_start_timer(bat_priv);
batadv_tvlv_handler_register(bat_priv, batadv_dat_tvlv_ogm_handler_v1,