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Fencer Vulns
high 7.8

CVE-2022-49554 json

zsmalloc: fix races between asynchronous zspage free and page migration

published 2025-02-26 20 mo ago modified 2026-10-15 24 d ago also EUVD-2022-54678

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 12%
public exploits
0
none known

Summary

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

zsmalloc: fix races between asynchronous zspage free and page migration

The asynchronous zspage free worker tries to lock a zspage's entire page list without defending against page migration. Since pages which haven't yet been locked can concurrently migrate off the zspage page list while lock_zspage() churns away, lock_zspage() can suffer from a few different lethal races.

It can lock a page which no longer belongs to the zspage and unsafely dereference page_private(), it can unsafely dereference a torn pointer to the next page (since there's a data race), and it can observe a spurious NULL pointer to the next page and thus not lock all of the zspage's pages (since a single page migration will reconstruct the entire page list, and create_page_chain() unconditionally zeroes out each list pointer in the process).

Fix the races by using migrate_read_lock() in lock_zspage() to synchronize with page migration.

Patch / fix

  • Linux Linux 4.14.282, 4.19.246, 5.4.197, 5.10.120, 5.15.45, 5.17.13, 5.18.2, 5.19
  • linux Debian 14, Debian 13, Debian 12 5.18.2-1

debian advisories DEBIAN-CVE-2022-49554

  • linux Ubuntu 18.04 LTS 4.15.0-191.202
  • linux Ubuntu 20.04 LTS 5.4.0-126.142
  • linux Ubuntu 22.04 LTS 5.15.0-47.51
  • linux-aws Ubuntu 18.04 LTS 4.15.0-1139.150
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1085.92
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1019.23
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1089.97
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1017.23

ubuntu advisories UBUNTU-CVE-2022-49554

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-2022-49554 updated cvss 5.5

kernel: zsmalloc: fix races between asynchronous zspage free and page migration

  • Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more
    affected: no fix available “Fix deferred”
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 10 kernel
    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
total
Assessed
24 d ago

Exploit prediction

0.22% chance of exploitation in the next 30 days, higher than 12% 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 4.7 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Linux Linux

Classification

Weakness
  • CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.