CVE-2024-56672

HIGH EPSS 18.9%
Published Dec 27, 20241y ago · Modified Jun 17, 20261w ago
7.0 CVSS 3.1
High
Find Similar
Published Dec 27, 2024 1y ago
Last Modified Jun 17, 2026 1w ago

Description

In the Linux kernel, the following vulnerability has been resolved: blk-cgroup: Fix UAF in blkcg_unpin_online() blkcg_unpin_online() walks up the blkcg hierarchy putting the online pin. To walk up, it uses blkcg_parent(blkcg) but it was calling that after blkcg_destroy_blkgs(blkcg) which could free the blkcg, leading to the following UAF: ================================================================== BUG: KASAN: slab-use-after-free in blkcg_unpin_online+0x15a/0x270 Read of size 8 at addr ffff8881057678c0 by task kworker/9:1/117 CPU: 9 UID: 0 PID: 117 Comm: kworker/9:1 Not tainted 6.13.0-rc1-work-00182-gb8f52214c61a-dirty #48 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS unknown 02/02/2022 Workqueue: cgwb_release cgwb_release_workfn Call Trace: <TASK> dump_stack_lvl+0x27/0x80 print_report+0x151/0x710 kasan_report+0xc0/0x100 blkcg_unpin_online+0x15a/0x270 cgwb_release_workfn+0x194/0x480 process_scheduled_works+0x71b/0xe20 worker_thread+0x82a/0xbd0 kthread+0x242/0x2c0 ret_from_fork+0x33/0x70 ret_from_fork_asm+0x1a/0x30 </TASK> ... Freed by task 1944: kasan_save_track+0x2b/0x70 kasan_save_free_info+0x3c/0x50 __kasan_slab_free+0x33/0x50 kfree+0x10c/0x330 css_free_rwork_fn+0xe6/0xb30 process_scheduled_works+0x71b/0xe20 worker_thread+0x82a/0xbd0 kthread+0x242/0x2c0 ret_from_fork+0x33/0x70 ret_from_fork_asm+0x1a/0x30 Note that the UAF is not easy to trigger as the free path is indirected behind a couple RCU grace periods and a work item execution. I could only trigger it with artifical msleep() injected in blkcg_unpin_online(). Fix it by reading the parent pointer before destroying the blkcg's blkg's.

CVSS Details

Base Score
7.0
Exploitability
1.0
Impact
5.9
Vector string
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack Vector Local
Attack Complexity High
Privileges Required Low
User Interaction None
Scope Unchanged
Confidentiality High
Integrity High
Availability High

Threat Intelligence

EPSS Exploit Probability
18.9% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-416 Use After Free Memory Safety

Affected Products 5

VendorProductVersionRange
linuxlinux_kernel*≥5.7  –  <6.1.121
linuxlinux_kernel*≥6.2  –  <6.6.67
linuxlinux_kernel*≥6.7  –  <6.12.6
linuxlinux_kernel6.13any
linuxlinux_kernel6.13any

References 9

  • cert-portal.siemens.com https://cert-portal.siemens.com/productcert/html/ssa-265688.html
  • git.kernel.org https://git.kernel.org/stable/c/29d1e06560f0f6179062ac638b4064deb637d1ad
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/5baa28569c924d9a90d036c2aaab79f791fedaf8
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/64afc6fe24c9896c0153e5a199bcea241ecb0d5c
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/83f5a87ee8caa76a917f59912a74d6811f773c67
  • git.kernel.org https://git.kernel.org/stable/c/86e6ca55b83c575ab0f2e105cf08f98e58d3d7af
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/8a07350fe070017a887433f4d6909433955be5f1
  • lists.debian.org https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html
  • lists.debian.org https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html

Remediation

  • git.kernel.org https://git.kernel.org/stable/c/29d1e06560f0f6179062ac638b4064deb637d1ad
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/5baa28569c924d9a90d036c2aaab79f791fedaf8
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/64afc6fe24c9896c0153e5a199bcea241ecb0d5c
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/86e6ca55b83c575ab0f2e105cf08f98e58d3d7af
    Patch