CVE-2023-52468

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

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

The lock_class_key is still registered and can be found in lock_keys_hash hlist after subsys_private is freed in error handler path.A task who iterate over the lock_keys_hash later may cause use-after-free.So fix that up and unregister the lock_class_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 lockdep_register_key+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: dump_backtrace+0x1b0/0x1e4 show_stack+0x2c/0x40 dump_stack_lvl+0xac/0xe0 print_report+0x18c/0x4d8 kasan_report+0xe8/0x148 __hwasan_store8_noabort+0x88/0x98 lockdep_register_key+0x19c/0x1bc class_register+0x94/0x1ec init_module+0xbc/0xf48 [rfkill] do_one_initcall+0x17c/0x72c do_init_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 CONFIG_KASAN_GENERIC is not set, Kasan reports invalid-access not use-after-free here.In this case, modprobe is manipulating the corrupted lock_keys_hash hlish where lock_class_key is already freed before.

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

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/0f1486dafca3398c4c46b9f6e6452fa27e73b559
• https://git.kernel.org/stable/c/93ec4a3b76404bce01bd5c9032bef5df6feb1d62
• https://git.kernel.org/stable/c/b57196a5ec5e4c0ffecde8348b085b778c7dce04
• https://git.kernel.org/stable/c/0f1486dafca3398c4c46b9f6e6452fa27e73b559
• https://git.kernel.org/stable/c/93ec4a3b76404bce01bd5c9032bef5df6feb1d62
• https://git.kernel.org/stable/c/b57196a5ec5e4c0ffecde8348b085b778c7dce04