In the Linux kernel, the following vulnerability has been resolved:
watchdog: pretimeout: Fix UAF in watchdog_unregister_governor()
When a watchdog governor is unregistered, it updates existing watchdog
devices that were using this governor by falling back to default_gov.
If the governor being unregistered is currently set as default_gov,
the default_gov is never cleared. This leads to 2 use-after-free
issues:
- New watchdog devices registered after this point will inherit the
dangling
default_gov. - Existing watchdog devices using the unregistered governor will have
their
wdd->govreassigned to the danglingdefault_gov.
Fix the UAF by clearing default_gov if it matches the governor being
unregistered.
References
- https://git.kernel.org/stable/c/0ca252720f0e38411cfec3431db9bb1aed0a412c
- https://git.kernel.org/stable/c/2e47b91b9b4020fcc01def14d6b6556d66074cf4
- https://git.kernel.org/stable/c/7362ba0f9c96ac3ad6a2ca3995bd9fc9a28a8661
- https://git.kernel.org/stable/c/7993d626983cc58fbde9607333cfd2d57725c197
- https://git.kernel.org/stable/c/7d1658b066de30f4b23afc14814d22416a971e6e