Skip to content
Fencer Vulns
medium 5.5

CVE-2021-47623 json

powerpc/fixmap: Fix VM debug warning on unmap

published 2024-07-16 2 y ago modified 2026-06-17 4 mo ago also EUVD-2021-34624

cvss
5.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 13%
public exploits
0
none known

Summary

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

powerpc/fixmap: Fix VM debug warning on unmap

Unmapping a fixmap entry is done by calling __set_fixmap() with FIXMAP_PAGE_CLEAR as flags.

Today, powerpc __set_fixmap() calls map_kernel_page().

map_kernel_page() is not happy when called a second time for the same page.

WARNING: CPU: 0 PID: 1 at arch/powerpc/mm/pgtable.c:194 set_pte_at+0xc/0x1e8 CPU: 0 PID: 1 Comm: swapper Not tainted 5.16.0-rc3-s3k-dev-01993-g350ff07feb7d-dirty #682 NIP: c0017cd4 LR: c00187f0 CTR: 00000010 REGS: e1011d50 TRAP: 0700 Not tainted (5.16.0-rc3-s3k-dev-01993-g350ff07feb7d-dirty) MSR: 00029032 <EE,ME,IR,DR,RI> CR: 42000208 XER: 00000000

GPR00: c0165fec e1011e10 c14c0000 c0ee2550 ff800000 c0f3d000 00000000 c001686c GPR08: 00001000 b00045a9 00000001 c0f58460 c0f50000 00000000 c0007e10 00000000 GPR16: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 GPR24: 00000000 00000000 c0ee2550 00000000 c0f57000 00000ff8 00000000 ff800000 NIP [c0017cd4] set_pte_at+0xc/0x1e8 LR [c00187f0] map_kernel_page+0x9c/0x100 Call Trace: [e1011e10] [c0736c68] vsnprintf+0x358/0x6c8 (unreliable) [e1011e30] [c0165fec] __set_fixmap+0x30/0x44 [e1011e40] [c0c13bdc] early_iounmap+0x11c/0x170 [e1011e70] [c0c06cb0] ioremap_legacy_serial_console+0x88/0xc0 [e1011e90] [c0c03634] do_one_initcall+0x80/0x178 [e1011ef0] [c0c0385c] kernel_init_freeable+0xb4/0x250 [e1011f20] [c0007e34] kernel_init+0x24/0x140 [e1011f30] [c0016268] ret_from_kernel_thread+0x5c/0x64 Instruction dump: 7fe3fb78 48019689 80010014 7c630034 83e1000c 5463d97e 7c0803a6 38210010 4e800020 81250000 712a0001 41820008 <0fe00000> 9421ffe0 93e1001c 48000030

Implement unmap_kernel_page() which clears an existing pte.

Patch / fix

  • Linux Linux 5.10.101, 5.15.24, 5.16.10, 5.17
  • linux Debian 14, Debian 13, Debian 12 5.16.10-1

debian advisories DEBIAN-CVE-2021-47623

  • linux-intel-iotg-5.15 Ubuntu 20.04 LTS 5.15.0-1008.11~20.04.1

ubuntu advisories UBUNTU-CVE-2021-47623

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 9.0 E4S 5.14.0-70.117.1.el9_0
  • perf RHEL 9.0 E4S 5.14.0-70.117.1.el9_0
  • bpftool RHEL 9.0 E4S 5.14.0-70.117.1.el9_0
  • kernel-core RHEL 9.0 E4S 5.14.0-70.117.1.el9_0
  • kernel-tools RHEL 9.0 E4S 5.14.0-70.117.1.el9_0
  • python3-perf RHEL 9.0 E4S 5.14.0-70.117.1.el9_0
  • kernel-modules RHEL 9.0 E4S 5.14.0-70.117.1.el9_0
  • kernel-zfcpdump RHEL 9.0 E4S 5.14.0-70.117.1.el9_0

red hat advisories RHSA-2024:6991

  • kernel-azure SLE Module for Public Cloud 15 SP5, openSUSE Leap 15.5 5.14.21-150500.33.63.1
  • kernel-syms-azure SLE Module for Public Cloud 15 SP5, openSUSE Leap 15.5 5.14.21-150500.33.63.1
  • kernel-source-azure SLE Module for Public Cloud 15 SP5, openSUSE Leap 15.5 5.14.21-150500.33.63.1
  • dtb-aarch64 openSUSE Leap 15.5 5.14.21-150500.55.73.1
  • kernel-64kb SLE Module for Basesystem 15 SP5, openSUSE Leap 15.5 5.14.21-150500.55.73.1
  • kernel-syms SLE Module for Development Tools 15 SP5, openSUSE Leap 15.5 5.14.21-150500.55.73.1
  • kernel-obs-qa openSUSE Leap 15.5 5.14.21-150500.55.73.1
  • kernel-source SLE Module for Development Tools 15 SP5, SLE Module for Basesystem 15 SP5, openSUSE Leap 15.5 5.14.21-150500.55.73.1

suse advisories SUSE-SU-2024:2947-1SUSE-SU-2024:2939-1SUSE-SU-2024:2894-1

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-2021-47623 updated cvss 4.4

kernel: powerpc/fixmap: Fix VM debug warning on unmap

  • 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
    affected: no fix planned “Out of support scope”
  • 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
    affected: no fix available “Fix deferred”
  • Red Hat Enterprise Linux AppStream E4S (v.9.0) perf 5.14.0-70.117.1.el9_0, kernel-devel-matched 5.14.0-70.117.1.el9_0, kernel-debug-devel-matched 5.14.0-70.117.1.el9_0, kernel-debuginfo-common-s390x 5.14.0-70.117.1.el9_0, kernel-zfcpdump-devel-matched 5.14.0-70.117.1.el9_0, kernel-debuginfo-common-x86_64 5.14.0-70.117.1.el9_0, +2 more Red Hat Enterprise Linux BaseOS E4S (v.9.0) kernel 5.14.0-70.117.1.el9_0, bpftool 5.14.0-70.117.1.el9_0, kernel-core 5.14.0-70.117.1.el9_0, kernel-tools 5.14.0-70.117.1.el9_0, python3-perf 5.14.0-70.117.1.el9_0, kernel-modules 5.14.0-70.117.1.el9_0, +14 more
    fixed: vendor fix RHSA-2024:6991

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

0.22% chance of exploitation in the next 30 days, higher than 13% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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.