CVE-2024-43853

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Source
https://cve.org/CVERecord?id=CVE-2024-43853
Import Source
https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2024-43853.json
JSON Data
https://api.test.osv.dev/v1/vulns/CVE-2024-43853
Downstream
Related
Published
2024-08-17T09:22:10Z
Modified
2026-08-12T03:30:51Z
Severity
  • 7.0 (High) CVSS_V3 - CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H CVSS Calculator
Summary
cgroup/cpuset: Prevent UAF in proc_cpuset_show()
Details

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

cgroup/cpuset: Prevent UAF in proc_cpuset_show()

An UAF can happen when /proc/cpuset is read as reported in [1].

This can be reproduced by the following methods: 1.add an mdelay(1000) before acquiring the cgroup_lock In the cgroup_path_ns function. 2.$cat /proc//cpuset repeatly. 3.$mount -t cgroup -o cpuset cpuset /sys/fs/cgroup/cpuset/ $umount /sys/fs/cgroup/cpuset/ repeatly.

The race that cause this bug can be shown as below:

(umount) | (cat /proc//cpuset) css_release | proc_cpuset_show css_release_work_fn | css = task_get_css(tsk, cpuset_cgrp_id); css_free_rwork_fn | cgroup_path_ns(css->cgroup, ...); cgroup_destroy_root | mutex_lock(&cgroup_mutex); rebind_subsystems | cgroup_free_root | | // cgrp was freed, UAF | cgroup_path_ns_locked(cgrp,..);

When the cpuset is initialized, the root node top_cpuset.css.cgrp will point to &cgrp_dfl_root.cgrp. In cgroup v1, the mount operation will allocate cgroup_root, and top_cpuset.css.cgrp will point to the allocated &cgroup_root.cgrp. When the umount operation is executed, top_cpuset.css.cgrp will be rebound to &cgrp_dfl_root.cgrp.

The problem is that when rebinding to cgrp_dfl_root, there are cases where the cgroup_root allocated by setting up the root for cgroup v1 is cached. This could lead to a Use-After-Free (UAF) if it is subsequently freed. The descendant cgroups of cgroup v1 can only be freed after the css is released. However, the css of the root will never be released, yet the cgroup_root should be freed when it is unmounted. This means that obtaining a reference to the css of the root does not guarantee that css.cgrp->root will not be freed.

Fix this problem by using rcu_read_lock in proc_cpuset_show(). As cgroup_root is kfree_rcu after commit d23b5c577715 ("cgroup: Make operations on the cgroup root_list RCU safe"), css->cgroup won't be freed during the critical section. To call cgroup_path_ns_locked, css_set_lock is needed, so it is safe to replace task_get_css with task_css.

[1] https://syzkaller.appspot.com/bug?extid=9b1ff7be974a403aa4cd

Database specific 
{
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/43xxx/CVE-2024-43853.json"
}
References

Affected packages

Git / git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git

Affected ranges

Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
a79a908fd2b080977b45bf103184b81c9d11ad07
Fixed
27d6dbdc6485d68075a0ebf8544d6425c1ed84bb
Fixed
10aeaa47e4aa2432f29b3e5376df96d7dac5537a
Fixed
688325078a8b5badd6e07ae22b27cd04e9947aec
Fixed
4e8d6ac8fc9f843e940ab7389db8136634e07989
Fixed
29a8d4e02fd4840028c38ceb1536cc8f82a257d4
Fixed
96226fbed566f3f686f53a489a29846f2d538080
Fixed
29ac1d238b3bf126af36037df80d7ecc4822341e
Fixed
1be59c97c83ccd67a519d8a49486b3a8a73ca28a

Database specific

source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2024-43853.json"

Linux / Kernel

Package

Name
Kernel

Affected ranges

Type
ECOSYSTEM
Events
Introduced
4.6.0
Fixed
4.19.321
Type
ECOSYSTEM
Events
Introduced
4.20.0
Fixed
5.4.283
Type
ECOSYSTEM
Events
Introduced
5.5.0
Fixed
5.10.225
Type
ECOSYSTEM
Events
Introduced
5.11.0
Fixed
5.15.166
Type
ECOSYSTEM
Events
Introduced
5.16.0
Fixed
6.1.103
Type
ECOSYSTEM
Events
Introduced
6.2.0
Fixed
6.6.44
Type
ECOSYSTEM
Events
Introduced
6.7.0
Fixed
6.10.3

Database specific

source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2024-43853.json"