GHSA-CW5R-8WJ2-XPQF

Vulnerability from github – Published: 2024-05-21 18:31 – Updated: 2025-01-06 21:30
VLAI
Details

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

sched/psi: Fix use-after-free in ep_remove_wait_queue()

If a non-root cgroup gets removed when there is a thread that registered trigger and is polling on a pressure file within the cgroup, the polling waitqueue gets freed in the following path:

do_rmdir cgroup_rmdir kernfs_drain_open_files cgroup_file_release cgroup_pressure_release psi_trigger_destroy

However, the polling thread still has a reference to the pressure file and will access the freed waitqueue when the file is closed or upon exit:

fput ep_eventpoll_release ep_free ep_remove_wait_queue remove_wait_queue

This results in use-after-free as pasted below.

The fundamental problem here is that cgroup_file_release() (and consequently waitqueue's lifetime) is not tied to the file's real lifetime. Using wake_up_pollfree() here might be less than ideal, but it is in line with the comment at commit 42288cb44c4b ("wait: add wake_up_pollfree()") since the waitqueue's lifetime is not tied to file's one and can be considered as another special case. While this would be fixable by somehow making cgroup_file_release() be tied to the fput(), it would require sizable refactoring at cgroups or higher layer which might be more justifiable if we identify more cases like this.

BUG: KASAN: use-after-free in _raw_spin_lock_irqsave+0x60/0xc0 Write of size 4 at addr ffff88810e625328 by task a.out/4404

CPU: 19 PID: 4404 Comm: a.out Not tainted 6.2.0-rc6 #38
Hardware name: Amazon EC2 c5a.8xlarge/, BIOS 1.0 10/16/2017
Call Trace:
<TASK>
dump_stack_lvl+0x73/0xa0
print_report+0x16c/0x4e0
kasan_report+0xc3/0xf0
kasan_check_range+0x2d2/0x310
_raw_spin_lock_irqsave+0x60/0xc0
remove_wait_queue+0x1a/0xa0
ep_free+0x12c/0x170
ep_eventpoll_release+0x26/0x30
__fput+0x202/0x400
task_work_run+0x11d/0x170
do_exit+0x495/0x1130
do_group_exit+0x100/0x100
get_signal+0xd67/0xde0
arch_do_signal_or_restart+0x2a/0x2b0
exit_to_user_mode_prepare+0x94/0x100
syscall_exit_to_user_mode+0x20/0x40
do_syscall_64+0x52/0x90
entry_SYSCALL_64_after_hwframe+0x63/0xcd
</TASK>

Allocated by task 4404:

kasan_set_track+0x3d/0x60
__kasan_kmalloc+0x85/0x90
psi_trigger_create+0x113/0x3e0
pressure_write+0x146/0x2e0
cgroup_file_write+0x11c/0x250
kernfs_fop_write_iter+0x186/0x220
vfs_write+0x3d8/0x5c0
ksys_write+0x90/0x110
do_syscall_64+0x43/0x90
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Freed by task 4407:

kasan_set_track+0x3d/0x60
kasan_save_free_info+0x27/0x40
____kasan_slab_free+0x11d/0x170
slab_free_freelist_hook+0x87/0x150
__kmem_cache_free+0xcb/0x180
psi_trigger_destroy+0x2e8/0x310
cgroup_file_release+0x4f/0xb0
kernfs_drain_open_files+0x165/0x1f0
kernfs_drain+0x162/0x1a0
__kernfs_remove+0x1fb/0x310
kernfs_remove_by_name_ns+0x95/0xe0
cgroup_addrm_files+0x67f/0x700
cgroup_destroy_locked+0x283/0x3c0
cgroup_rmdir+0x29/0x100
kernfs_iop_rmdir+0xd1/0x140
vfs_rmdir+0xfe/0x240
do_rmdir+0x13d/0x280
__x64_sys_rmdir+0x2c/0x30
do_syscall_64+0x43/0x90
entry_SYSCALL_64_after_hwframe+0x63/0xcd
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Show details on source website
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{
  "affected": [],
  "aliases": [
    "CVE-2023-52707"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-416"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-05-21T16:15:12Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsched/psi: Fix use-after-free in ep_remove_wait_queue()\n\nIf a non-root cgroup gets removed when there is a thread that registered\ntrigger and is polling on a pressure file within the cgroup, the polling\nwaitqueue gets freed in the following path:\n\n do_rmdir\n   cgroup_rmdir\n     kernfs_drain_open_files\n       cgroup_file_release\n         cgroup_pressure_release\n           psi_trigger_destroy\n\nHowever, the polling thread still has a reference to the pressure file and\nwill access the freed waitqueue when the file is closed or upon exit:\n\n fput\n   ep_eventpoll_release\n     ep_free\n       ep_remove_wait_queue\n         remove_wait_queue\n\nThis results in use-after-free as pasted below.\n\nThe fundamental problem here is that cgroup_file_release() (and\nconsequently waitqueue\u0027s lifetime) is not tied to the file\u0027s real lifetime.\nUsing wake_up_pollfree() here might be less than ideal, but it is in line\nwith the comment at commit 42288cb44c4b (\"wait: add wake_up_pollfree()\")\nsince the waitqueue\u0027s lifetime is not tied to file\u0027s one and can be\nconsidered as another special case. While this would be fixable by somehow\nmaking cgroup_file_release() be tied to the fput(), it would require\nsizable refactoring at cgroups or higher layer which might be more\njustifiable if we identify more cases like this.\n\n  BUG: KASAN: use-after-free in _raw_spin_lock_irqsave+0x60/0xc0\n  Write of size 4 at addr ffff88810e625328 by task a.out/4404\n\n\tCPU: 19 PID: 4404 Comm: a.out Not tainted 6.2.0-rc6 #38\n\tHardware name: Amazon EC2 c5a.8xlarge/, BIOS 1.0 10/16/2017\n\tCall Trace:\n\t\u003cTASK\u003e\n\tdump_stack_lvl+0x73/0xa0\n\tprint_report+0x16c/0x4e0\n\tkasan_report+0xc3/0xf0\n\tkasan_check_range+0x2d2/0x310\n\t_raw_spin_lock_irqsave+0x60/0xc0\n\tremove_wait_queue+0x1a/0xa0\n\tep_free+0x12c/0x170\n\tep_eventpoll_release+0x26/0x30\n\t__fput+0x202/0x400\n\ttask_work_run+0x11d/0x170\n\tdo_exit+0x495/0x1130\n\tdo_group_exit+0x100/0x100\n\tget_signal+0xd67/0xde0\n\tarch_do_signal_or_restart+0x2a/0x2b0\n\texit_to_user_mode_prepare+0x94/0x100\n\tsyscall_exit_to_user_mode+0x20/0x40\n\tdo_syscall_64+0x52/0x90\n\tentry_SYSCALL_64_after_hwframe+0x63/0xcd\n\t\u003c/TASK\u003e\n\n Allocated by task 4404:\n\n\tkasan_set_track+0x3d/0x60\n\t__kasan_kmalloc+0x85/0x90\n\tpsi_trigger_create+0x113/0x3e0\n\tpressure_write+0x146/0x2e0\n\tcgroup_file_write+0x11c/0x250\n\tkernfs_fop_write_iter+0x186/0x220\n\tvfs_write+0x3d8/0x5c0\n\tksys_write+0x90/0x110\n\tdo_syscall_64+0x43/0x90\n\tentry_SYSCALL_64_after_hwframe+0x63/0xcd\n\n Freed by task 4407:\n\n\tkasan_set_track+0x3d/0x60\n\tkasan_save_free_info+0x27/0x40\n\t____kasan_slab_free+0x11d/0x170\n\tslab_free_freelist_hook+0x87/0x150\n\t__kmem_cache_free+0xcb/0x180\n\tpsi_trigger_destroy+0x2e8/0x310\n\tcgroup_file_release+0x4f/0xb0\n\tkernfs_drain_open_files+0x165/0x1f0\n\tkernfs_drain+0x162/0x1a0\n\t__kernfs_remove+0x1fb/0x310\n\tkernfs_remove_by_name_ns+0x95/0xe0\n\tcgroup_addrm_files+0x67f/0x700\n\tcgroup_destroy_locked+0x283/0x3c0\n\tcgroup_rmdir+0x29/0x100\n\tkernfs_iop_rmdir+0xd1/0x140\n\tvfs_rmdir+0xfe/0x240\n\tdo_rmdir+0x13d/0x280\n\t__x64_sys_rmdir+0x2c/0x30\n\tdo_syscall_64+0x43/0x90\n\tentry_SYSCALL_64_after_hwframe+0x63/0xcd",
  "id": "GHSA-cw5r-8wj2-xpqf",
  "modified": "2025-01-06T21:30:49Z",
  "published": "2024-05-21T18:31:19Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-52707"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7caeb5457bd01ccba0df1d6f4872f20d28e50b38"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c2dbe32d5db5c4ead121cf86dabd5ab691fb47fe"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c6879a4dcefe92d870ab68cabaa9caeda4f2af5a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cca2b3feb70170ef6f0fbc4b4d91eea235a2b73a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ec9c7aa08819f976b2492fa63c41b5712d2924b5"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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