In the Linux kernel, the following vulnerability has been resolved:
watchdog: unregister PM notifier on watchdog unregister
watchdog_register_device() registers wdd->pm_nb when WDOG_NO_PING_ON_SUSPEND is set, but watchdog_unregister_device() does not remove it. This leaves an embedded notifier block on the PM notifier chain after the watchdog device has been unregistered.
A later suspend/resume notification can then call watchdog_pm_notifier() with a stale watchdog_device pointer, or at minimum after wdd->wd_data has been cleared by watchdog_dev_unregister().
Unregister the PM notifier before tearing down the watchdog device.
References
- https://git.kernel.org/stable/c/298821692d447c2f7b1bc9ef41cd88a31bf56436
- https://git.kernel.org/stable/c/5d9b58ec6f5de5e159a570d419b1b08b3b9f854b
- https://git.kernel.org/stable/c/89184909634e50d086d86d8a0c03fc86fe8d889f
- https://git.kernel.org/stable/c/a298c7302ee9584a7a1ac1e8acbede8d98ab51a4
- https://git.kernel.org/stable/c/c70b5bb6f04f77ef90e047d7edc2f476e206909f
- https://git.kernel.org/stable/c/cd2d1b1f99308f7680d75a377daaff363f1cc736
- https://git.kernel.org/stable/c/e690afea5c876a4abfa2978c6a664460ed7d1217