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CVE-2024-56672 Detail

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.


Metrics

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CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
N/A
NVD assessment not yet provided.

References to Advisories, Solutions, and Tools

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Hyperlink Resource
https://git.kernel.org/stable/c/29d1e06560f0f6179062ac638b4064deb637d1ad Patch 
https://git.kernel.org/stable/c/5baa28569c924d9a90d036c2aaab79f791fedaf8 Patch 
https://git.kernel.org/stable/c/64afc6fe24c9896c0153e5a199bcea241ecb0d5c Patch 
https://git.kernel.org/stable/c/83f5a87ee8caa76a917f59912a74d6811f773c67
https://git.kernel.org/stable/c/86e6ca55b83c575ab0f2e105cf08f98e58d3d7af Patch 
https://git.kernel.org/stable/c/8a07350fe070017a887433f4d6909433955be5f1

Weakness Enumeration

CWE-ID CWE Name Source
CWE-416 Use After Free cwe source acceptance level NIST  

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Change History

4 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2024-56672
NVD Published Date:
12/27/2024
NVD Last Modified:
02/02/2025
Source:
kernel.org