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Fencer Vulns
medium 5.5

CVE-2022-49955 json

powerpc/rtas: Fix RTAS MSR[HV] handling for Cell

published 2025-06-18 16 mo ago modified 2026-11-05 3 d ago also EUVD-2022-55237

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 11%
public exploits
0
none known

Summary

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

powerpc/rtas: Fix RTAS MSR[HV] handling for Cell

The semi-recent changes to MSR handling when entering RTAS (firmware) cause crashes on IBM Cell machines. An example trace:

kernel tried to execute user page (2fff01a8) - exploit attempt? (uid: 0) BUG: Unable to handle kernel instruction fetch Faulting instruction address: 0x2fff01a8 Oops: Kernel access of bad area, sig: 11 [#1] BE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=4 NUMA Cell Modules linked in: CPU: 0 PID: 0 Comm: swapper/0 Tainted: G W 6.0.0-rc2-00433-gede0a8d3307a #207 NIP: 000000002fff01a8 LR: 0000000000032608 CTR: 0000000000000000 REGS: c0000000015236b0 TRAP: 0400 Tainted: G W (6.0.0-rc2-00433-gede0a8d3307a) MSR: 0000000008001002 <ME,RI> CR: 00000000 XER: 20000000 ... NIP 0x2fff01a8 LR 0x32608 Call Trace: 0xc00000000143c5f8 (unreliable) .rtas_call+0x224/0x320 .rtas_get_boot_time+0x70/0x150 .read_persistent_clock64+0x114/0x140 .read_persistent_wall_and_boot_offset+0x24/0x80 .timekeeping_init+0x40/0x29c .start_kernel+0x674/0x8f0 start_here_common+0x1c/0x50

Unlike PAPR platforms where RTAS is only used in guests, on the IBM Cell machines Linux runs with MSR[HV] set but also uses RTAS, provided by SLOF.

Fix it by copying the MSR[HV] bit from the MSR value we've just read using mfmsr into the value used for RTAS.

It seems like we could also fix it using an #ifdef CELL to set MSR[HV], but that doesn't work because it's possible to build a single kernel image that runs on both Cell native and pseries.

Patch / fix

  • Linux Linux 5.16, 5.18, 5.19, 5.19.8, 6.0
  • linux Debian 14, Debian 13, Debian 12 6.0.2-1

debian advisories DEBIAN-CVE-2022-49955

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-2022-49955 updated cvss 4.7

kernel: powerpc/rtas: Fix RTAS MSR[HV] handling for Cell

  • Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more
    affected: no fix available
  • 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 Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 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
partial
Assessed
3 d ago

Exploit prediction

0.21% chance of exploitation in the next 30 days, higher than 11% 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

Weakness
Technology feeds

References

Sources

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