CVE-2023-52468

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

class: fix use-after-free in class_register()

The lockclasskey is still registered and can be found in lockkeyshash hlist after subsysprivate is freed in error handler path.A task who iterate over the lockkeyshash later may cause use-after-free.So fix that up and unregister the lockclass_key before kfree(cp).

On our platform, a driver fails to kset_register because of creating duplicate filename '/class/xxx'.With Kasan enabled, it prints a invalid-access bug report.

KASAN bug report:

BUG: KASAN: invalid-access in lockdepregisterkey+0x19c/0x1bc Write of size 8 at addr 15ffff808b8c0368 by task modprobe/252 Pointer tag: [15], memory tag: [fe]

CPU: 7 PID: 252 Comm: modprobe Tainted: G W 6.6.0-mainline-maybe-dirty #1

Call trace: dumpbacktrace+0x1b0/0x1e4 showstack+0x2c/0x40 dumpstacklvl+0xac/0xe0 printreport+0x18c/0x4d8 kasanreport+0xe8/0x148 _hwasanstore8noabort+0x88/0x98 lockdepregisterkey+0x19c/0x1bc classregister+0x94/0x1ec initmodule+0xbc/0xf48 [rfkill] dooneinitcall+0x17c/0x72c doinit_module+0x19c/0x3f8 ... Memory state around the buggy address: ffffff808b8c0100: 8a 8a 8a 8a 8a 8a 8a 8a 8a 8a 8a 8a 8a 8a 8a 8a ffffff808b8c0200: 8a 8a 8a 8a 8a 8a 8a 8a fe fe fe fe fe fe fe fe

ffffff808b8c0300: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe ^ ffffff808b8c0400: 03 03 03 03 03 03 03 03 03 03 03 03 03 03 03 03

As CONFIGKASANGENERIC is not set, Kasan reports invalid-access not use-after-free here.In this case, modprobe is manipulating the corrupted lockkeyshash hlish where lockclasskey is already freed before.

It's worth noting that this only can happen if lockdep is enabled, which is not true for normal system.