In the Linux kernel, the following vulnerability has been resolved:

net: dsa: mv88e6xxx: avoid unregistering devlink regions which were never registered

Russell King reports that a system with mv88e6xxx dereferences a NULL
pointer when unbinding this driver:
https://lore.kernel.org/netdev/[email protected]/

The crash seems to be in devlink_region_destroy(), which is not NULL
tolerant but is given a NULL devlink global region pointer.

At least on some chips, some devlink regions are conditionally registered
since the blamed commit, see mv88e6xxx_setup_devlink_regions_global():

		if (cond && !cond(chip))
			continue;

These are MV88E6XXX_REGION_STU and MV88E6XXX_REGION_PVT. If the chip
does not have an STU or PVT, it should crash like this.

To fix the issue, avoid unregistering those regions which are NULL, i.e.
were skipped at mv88e6xxx_setup_devlink_regions_global() time.

https://git.kernel.org/stable/c/3665695e3572239dc233216f06b41f40cc771889

https://git.kernel.org/stable/c/5f5e95945bb1e08be7655da6acba648274db457d

https://git.kernel.org/stable/c/b3c70dfe51f10df60db2646c08cebd24bcdc5247

https://git.kernel.org/stable/c/bbb80f004f7a90c3dcaacc982c59967457254a05

https://git.kernel.org/stable/c/c84f6ce918a9e6f4996597cbc62536bbf2247c96