In the Linux kernel, the following vulnerability has been resolved:
e1000: Move cancel_work_sync to avoid deadlock
Previously, e1000_down called cancel_work_sync for the e1000 reset task
(via e1000_down_and_stop), which takes RTNL.
As reported by users and syzbot, a deadlock is possible in the following
scenario:
CPU 0:
- RTNL is held
- e1000_close
- e1000_down
- cancel_work_sync (cancel / wait for e1000_reset_task())
CPU 1:
- process_one_work
- e1000_reset_task
- take RTNL
To remedy this, avoid calling cancel_work_sync from e1000_down
(e1000_reset_task does nothing if the device is down anyway). Instead,
call cancel_work_sync for e1000_reset_task when the device is being
removed.