Affected: Linux

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.