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Fencer Vulns
high 7.8

CVE-2022-48892 json

sched/core: Fix use-after-free bug in dup_user_cpus_ptr()

published 2024-08-21 2 y ago modified 2026-08-05 3 mo ago also EUVD-2022-53771

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 16%
public exploits
0
none known

Summary

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

sched/core: Fix use-after-free bug in dup_user_cpus_ptr()

Since commit 07ec77a1d4e8 ("sched: Allow task CPU affinity to be restricted on asymmetric systems"), the setting and clearing of user_cpus_ptr are done under pi_lock for arm64 architecture. However, dup_user_cpus_ptr() accesses user_cpus_ptr without any lock protection. Since sched_setaffinity() can be invoked from another process, the process being modified may be undergoing fork() at the same time. When racing with the clearing of user_cpus_ptr in __set_cpus_allowed_ptr_locked(), it can lead to user-after-free and possibly double-free in arm64 kernel.

Commit 8f9ea86fdf99 ("sched: Always preserve the user requested cpumask") fixes this problem as user_cpus_ptr, once set, will never be cleared in a task's lifetime. However, this bug was re-introduced in commit 851a723e45d1 ("sched: Always clear user_cpus_ptr in do_set_cpus_allowed()") which allows the clearing of user_cpus_ptr in do_set_cpus_allowed(). This time, it will affect all arches.

Fix this bug by always clearing the user_cpus_ptr of the newly cloned/forked task before the copying process starts and check the user_cpus_ptr state of the source task under pi_lock.

Note to stable, this patch won't be applicable to stable releases. Just copy the new dup_user_cpus_ptr() function over.

Patch / fix

  • Linux Linux 5.15.89, 6.1.7, 6.2
  • linux Debian 14, Debian 13, Debian 12 6.1.7-1

debian advisories DEBIAN-CVE-2022-48892

  • linux Ubuntu 22.04 LTS 5.15.0-70.77
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1034.38
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1032.40
  • linux-gke Ubuntu 22.04 LTS 5.15.0-1031.36
  • linux-ibm Ubuntu 22.04 LTS 5.15.0-1028.31
  • linux-kvm Ubuntu 22.04 LTS 5.15.0-1031.36
  • linux-azure Ubuntu 22.04 LTS 5.15.0-1036.43
  • linux-gkeop Ubuntu 22.04 LTS 5.15.0-1018.23

ubuntu advisories UBUNTU-CVE-2022-48892

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2022-48892 updated cvss 7.0

kernel: sched/core: Fix use-after-free bug in dup_user_cpus_ptr()

  • Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

0.25% chance of exploitation in the next 30 days, higher than 16% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Weakness
Technology feeds

References

Sources

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