When an AMT device is removed, pending delayed works can still access
the freed amt_dev structure, which may result in kernel crashes or
memory corruption.
amt_dev_stop() cancels req_wq and discovery_wq with
cancel_delayed_work_sync(), but these works can be scheduled again
from event_wq after the cancellation. This allows delayed works to
access the freed amt_dev structure after the netdev has been released.
The following is a simple race scenario:
CPU0 CPU1
amt_dev_stop()
cancel_delayed_work_sync()
amt_event_work()
mod_delayed_work(req_wq)
free netdev
req_wq accesses freed amt_dev
Use disable_delayed_work_sync() in amt_dev_stop() to prevent req_wq and
discovery_wq from being queued again and wait for running work items
to complete.
The delayed works are disabled after initialization in
amt_newlink() and enabled only when the device is successfully opened.
This keeps the delayed work lifecycle synchronized with the lifetime
of the AMT device.
Fixes: cbc21dc1cf ("amt: add data plane of amt interface")
Cc: stable@vger.kernel.org
Signed-off-by: Shihuang Liu <shlomojune6@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Taehee Yoo <ap420073@gmail.com>
Link: https://patch.msgid.link/20260722113919.7723-1-shlomojune6@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
ea20c44935