> Since c578123e63da ("virtio_balloon: Treat stats requests as wakeup
> events") the stats_request() virtqueue callback takes vb->wakeup_lock
> via start_wakeup_event(). init_vqs() registers that callback and even
> primes and kicks the stats queue, so the lock is reachable from irq
> context as soon as init_vqs() returns, long before the driver sets
> DRIVER_OK: vring_interrupt() dispatches to the callback without any
> DRIVER_OK check unless CONFIG_VIRTIO_HARDEN_NOTIFICATION is set, and
> that option depends on BROKEN. syzbot hit it from a threaded irq:
>
> INFO: trying to register non-static key in stats_request
> ...
> assign_lock_key
> register_lock_class
> lock_acquire
> rt_spin_lock
> [ ... ]
>
> Fixes: c578123e63da ("virtio_balloon: Treat stats requests as wakeup events")
> Reported-by: [email protected]
> Closes: https://syzkaller.appspot.com/bug?extid=13df72e0dc4be5c62215
> Signed-off-by: Mingbing Zhai <[email protected]>
Sashiko has reviewed this patch and found no issues. It looks great!
--
Sashiko AI review ยท
https://sashiko.dev/#/patchset/[email protected]?part=1
