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.

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

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