In the Linux kernel, the following vulnerability has been resolved:

vsock/virtio: flush works in dependency order

virtio_vsock_remove() stops the virtqueues and then flushes each work
item before freeing the enclosing virtio_vsock.  The current order does
not account for dependencies between those items: tx_work may queue
send_pkt_work, and send_pkt_work may queue rx_work.

In particular, send_pkt_work can set restart_rx and release tx_lock.
The remove path can then stop the queues and flush rx_work before
send_pkt_work queues it.  Although the later send_pkt_work flush waits
for that producer to finish, nothing waits for the newly queued rx_work,
so kfree(vsock) can race with it.

KASAN reported:

  BUG: KASAN: slab-use-after-free in
  virtio_transport_rx_work+0x487/0x4b0
  Read of size 8 at addr ffff888114c2b008 by task kworker/1:1/47
  Workqueue: virtio_vsock virtio_transport_rx_work
  Call Trace:
   virtio_transport_rx_work+0x487/0x4b0
   process_one_work+0x688/0x1120
   worker_thread+0x45b/0xd10
  Allocated by task 1:
   virtio_vsock_probe+0xef/0x6b0
  Freed by task 84:
   kfree+0x131/0x3c0
   virtio_vsock_remove+0xd1/0x100

Flush the works in producer-to-consumer order.  virtio_vsock_vqs_del()
has already disabled the queue callbacks and cleared the run flags, so
after tx_work and send_pkt_work are drained, no source remains that can
queue rx_work after its flush.