CVE-2021-47488

kernel: cgroup: Fix memory leak caused by missing cgroup_bpf_offline

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Published May 22, 2024 CVSS 3.1 · 4.4 Medium EPSS n/a KEV · Not listed

Description

This CVE ID has been rejected or withdrawn by its CVE Numbering Authority.

Affected Products

No data.

No data available yet.

Remediation

No solution or workaround provided in the CVE record

Tracking

Advisories

No advisories available

Metrics

No CVSS v4.0

Attack Vector Local

Attack Complexity Low

Privileges Required High

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

References

Link	Providers
https://lore.kernel.org/linux-cve-announce/2024052240-CVE-2021-47488-9c35@gregkh/T
https://nvd.nist.gov/vuln/detail/CVE-2021-47488
https://www.cve.org/CVERecord?id=CVE-2021-47488

History

Dec 5, 2024 2:45 PM References updated View changes

Type	Values Removed	Values Added
References	https://git.kernel.org/stable/c/01599bf7cc2b49c3d2be886cb438647dc25446ed https://git.kernel.org/stable/c/04f8ef5643bcd8bcde25dfdebef998aea480b2ba https://git.kernel.org/stable/c/b529f88d93884cf8ccafda793ee3d27b82fa578d

Dec 5, 2024 2:15 PM Title updated. Scoring metrics updated View changes

Type	Values Removed	Values Added
Title	cgroup: Fix memory leak caused by missing cgroup_bpf_offline	kernel: cgroup: Fix memory leak caused by missing cgroup_bpf_offline
Metrics	ssvc `{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}`

Dec 5, 2024 2:00 PM Description updated View changes

Type	Values Removed	Values Added
Description	In the Linux kernel, the following vulnerability has been resolved: cgroup: Fix memory leak caused by missing cgroup_bpf_offline When enabling CONFIG_CGROUP_BPF, kmemleak can be observed by running the command as below: $mount -t cgroup -o none,name=foo cgroup cgroup/ $umount cgroup/ unreferenced object 0xc3585c40 (size 64): comm "mount", pid 425, jiffies 4294959825 (age 31.990s) hex dump (first 32 bytes): 01 00 00 80 84 8c 28 c0 00 00 00 00 00 00 00 00 ......(......... 00 00 00 00 00 00 00 00 6c 43 a0 c3 00 00 00 00 ........lC...... backtrace: [<e95a2f9e>] cgroup_bpf_inherit+0x44/0x24c [<1f03679c>] cgroup_setup_root+0x174/0x37c [<ed4b0ac5>] cgroup1_get_tree+0x2c0/0x4a0 [<f85b12fd>] vfs_get_tree+0x24/0x108 [<f55aec5c>] path_mount+0x384/0x988 [<e2d5e9cd>] do_mount+0x64/0x9c [<208c9cfe>] sys_mount+0xfc/0x1f4 [<06dd06e0>] ret_fast_syscall+0x0/0x48 [<a8308cb3>] 0xbeb4daa8 This is because that since the commit 2b0d3d3e4fcf ("percpu_ref: reduce memory footprint of percpu_ref in fast path") root_cgrp->bpf.refcnt.data is allocated by the function percpu_ref_init in cgroup_bpf_inherit which is called by cgroup_setup_root when mounting, but not freed along with root_cgrp when umounting. Adding cgroup_bpf_offline which calls percpu_ref_kill to cgroup_kill_sb can free root_cgrp->bpf.refcnt.data in umount path. This patch also fixes the commit 4bfc0bb2c60e ("bpf: decouple the lifetime of cgroup_bpf from cgroup itself"). A cgroup_bpf_offline is needed to do a cleanup that frees the resources which are allocated by cgroup_bpf_inherit in cgroup_setup_root. And inside cgroup_bpf_offline, cgroup_get() is at the beginning and cgroup_put is at the end of cgroup_bpf_release which is called by cgroup_bpf_offline. So cgroup_bpf_offline can keep the balance of cgroup's refcount.	This CVE ID has been rejected or withdrawn by its CVE Numbering Authority.