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Fencer Vulns
high 7.1

CVE-2022-48943 json

KVM: x86/mmu: make apf token non-zero to fix bug

published 2024-08-22 2 y ago modified 2026-08-05 3 mo ago also EUVD-2022-53822

cvss
7.1
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:

KVM: x86/mmu: make apf token non-zero to fix bug

In current async pagefault logic, when a page is ready, KVM relies on kvm_arch_can_dequeue_async_page_present() to determine whether to deliver a READY event to the Guest. This function test token value of struct kvm_vcpu_pv_apf_data, which must be reset to zero by Guest kernel when a READY event is finished by Guest. If value is zero meaning that a READY event is done, so the KVM can deliver another. But the kvm_arch_setup_async_pf() may produce a valid token with zero value, which is confused with previous mention and may lead the loss of this READY event.

This bug may cause task blocked forever in Guest: INFO: task stress:7532 blocked for more than 1254 seconds. Not tainted 5.10.0 #16 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:stress state:D stack: 0 pid: 7532 ppid: 1409 flags:0x00000080 Call Trace: __schedule+0x1e7/0x650 schedule+0x46/0xb0 kvm_async_pf_task_wait_schedule+0xad/0xe0 ? exit_to_user_mode_prepare+0x60/0x70 __kvm_handle_async_pf+0x4f/0xb0 ? asm_exc_page_fault+0x8/0x30 exc_page_fault+0x6f/0x110 ? asm_exc_page_fault+0x8/0x30 asm_exc_page_fault+0x1e/0x30 RIP: 0033:0x402d00 RSP: 002b:00007ffd31912500 EFLAGS: 00010206 RAX: 0000000000071000 RBX: ffffffffffffffff RCX: 00000000021a32b0 RDX: 000000000007d011 RSI: 000000000007d000 RDI: 00000000021262b0 RBP: 00000000021262b0 R08: 0000000000000003 R09: 0000000000000086 R10: 00000000000000eb R11: 00007fefbdf2baa0 R12: 0000000000000000 R13: 0000000000000002 R14: 000000000007d000 R15: 0000000000001000

Patch / fix

  • Linux Linux 5.10.103, 5.15.26, 5.16.12, 5.17
  • linux Debian 14, Debian 13, Debian 12 5.16.12-1

debian advisories DEBIAN-CVE-2022-48943

  • linux Ubuntu 20.04 LTS 5.4.0-202.222
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1136.146
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1140.149
  • linux-ibm Ubuntu 20.04 LTS 5.4.0-1083.88
  • linux-iot Ubuntu 20.04 LTS 5.4.0-1045.46
  • linux-kvm Ubuntu 20.04 LTS 5.4.0-1124.132
  • linux-azure Ubuntu 20.04 LTS 5.4.0-1142.149
  • linux-raspi Ubuntu 20.04 LTS 5.4.0-1120.132

ubuntu advisories UBUNTU-CVE-2022-48943

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

  • kernel RHEL 9 5.14.0-162.6.1.el9_1
  • perf RHEL 9 5.14.0-162.6.1.el9_1
  • bpftool RHEL 9 5.14.0-162.6.1.el9_1
  • kernel-core RHEL 9 5.14.0-162.6.1.el9_1
  • kernel-tools RHEL 9 5.14.0-162.6.1.el9_1
  • python3-perf RHEL 9 5.14.0-162.6.1.el9_1
  • kernel-modules RHEL 9 5.14.0-162.6.1.el9_1
  • kernel-zfcpdump RHEL 9 5.14.0-162.6.1.el9_1

red hat advisories RHSA-2022:8267RHSA-2022:7683RHSA-2022:6460RHSA-2022:6003

  • kernel-azure SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-16.200.1
  • kernel-syms-azure SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-16.200.1
  • kernel-source-azure SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-16.200.1
  • kernel-rt SLE Real Time 12 SP5 4.12.14-10.203.1
  • kernel-syms-rt SLE Real Time 12 SP5 4.12.14-10.203.1
  • kernel-rt_debug SLE Real Time 12 SP5 4.12.14-10.203.1
  • kernel-source-rt SLE Real Time 12 SP5 4.12.14-10.203.1
  • kernel-syms SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-122.231.1

suse advisories SUSE-SU-2024:3591-1SUSE-SU-2024:3566-1SUSE-SU-2024:3559-1SUSE-SU-2024:3483-1SUSE-SU-2024:3408-1SUSE-SU-2024:3227-1

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-2022-48943 updated cvss 5.5

kernel: KVM: x86/mmu: make apf token non-zero to fix bug

  • Red Hat Enterprise Linux 8 kernel-rt, kernel-rt-kvm, kernel-rt-core, kernel-rt-modules, kernel-rt-debug-kvm, kernel-rt-debug-core, +6 more
    affected: no fix planned “Will not fix”
  • Red Hat Enterprise Linux 9 kernel-rt, kernel-rt-kvm, kernel-rt-core, kernel-rt-modules, kernel-rt-debug-kvm, kernel-rt-debug-core, +12 more
    affected: no fix available
  • Red Hat CodeReady Linux Builder (v. 8) kernel-debuginfo-common-x86_64 4.18.0-425.3.1.el8, kernel-debuginfo-common-aarch64 4.18.0-425.3.1.el8, kernel-debuginfo-common-ppc64le 4.18.0-425.3.1.el8
    fixed: vendor fix RHSA-2022:7683
  • Red Hat CodeReady Linux Builder (v. 9) kernel-debuginfo-common-s390x 5.14.0-162.6.1.el9_1, kernel-debuginfo-common-s390x 5.14.0-70.22.1.el9_0, kernel-debuginfo-common-x86_64 5.14.0-162.6.1.el9_1, kernel-debuginfo-common-x86_64 5.14.0-70.22.1.el9_0, kernel-debuginfo-common-aarch64 5.14.0-162.6.1.el9_1, kernel-debuginfo-common-aarch64 5.14.0-70.22.1.el9_0, +2 more Red Hat Enterprise Linux AppStream (v. 9) perf 5.14.0-162.6.1.el9_1, perf 5.14.0-70.22.1.el9_0, kernel-devel-matched 5.14.0-162.6.1.el9_1, kernel-devel-matched 5.14.0-70.22.1.el9_0, kernel-debug-devel-matched 5.14.0-162.6.1.el9_1, kernel-debug-devel-matched 5.14.0-70.22.1.el9_0, +10 more
    fixed: vendor fix RHSA-2022:6003
  • Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-425.3.1.el8, kernel 4.18.0-425.3.1.el8, bpftool 4.18.0-425.3.1.el8, perf 4.18.0-372.26.1.el8_6, kernel 4.18.0-372.26.1.el8_6, bpftool 4.18.0-372.26.1.el8_6, +36 more
    fixed: vendor fix RHSA-2022:6460
  • Red Hat Enterprise Linux BaseOS (v. 9) kernel 5.14.0-162.6.1.el9_1, kernel 5.14.0-70.22.1.el9_0, bpftool 5.14.0-162.6.1.el9_1, bpftool 5.14.0-70.22.1.el9_0, kernel-core 5.14.0-162.6.1.el9_1, kernel-core 5.14.0-70.22.1.el9_0, +34 more
    fixed: vendor fix RHSA-2022:6003
  • Red Hat Enterprise Linux CRB (v. 8) kernel-debuginfo-common-x86_64 4.18.0-372.26.1.el8_6, kernel-debuginfo-common-aarch64 4.18.0-372.26.1.el8_6, kernel-debuginfo-common-ppc64le 4.18.0-372.26.1.el8_6 Red Hat Virtualization 4 Hypervisor for RHEL 8 perf 4.18.0-372.26.1.el8_6, kernel-debuginfo-common-x86_64 4.18.0-372.26.1.el8_6
    fixed: vendor fix RHSA-2022:6460
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 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 7.1 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/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

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.