batman-adv: Broken sync while rescheduling delayed work
commit abac3ac9 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: 2f1dfbe1 ("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>
parent
f9b9c846
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