CVE-2023-52468 class: fix use-after-free in class_register()

2024-02-2508:16:32

Linux

github.com

linux kernel

use-after-free

vulnerability

fix

driver

kset_register

invalid-access

kasan

bug report

lockdep

enabled

6.7 Medium

AI Score

Confidence

Low

0.0004 Low

EPSS

Percentile

5.1%

JSON

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.

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

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/base/class.c"
    ],
    "versions": [
      {
        "version": "dcfbb67e48a2",
        "lessThan": "b57196a5ec5e",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "dcfbb67e48a2",
        "lessThan": "0f1486dafca3",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "dcfbb67e48a2",
        "lessThan": "93ec4a3b7640",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/base/class.c"
    ],
    "versions": [
      {
        "version": "6.4",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "6.4",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.6.14",
        "lessThanOrEqual": "6.6.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.7.2",
        "lessThanOrEqual": "6.7.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.8",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]