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.
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Tue, 01 Jul 2025 14:45:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

cvssV3_1

{'score': 4.7, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H'}


Tue, 01 Jul 2025 02:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-20
Metrics threat_severity

Moderate

threat_severity

Low


Sun, 22 Jun 2025 00:30:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

threat_severity

Moderate


Wed, 18 Jun 2025 11:15:00 +0000

Type Values Removed Values Added
Description 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.
Title powerpc/rtas: Fix RTAS MSR[HV] handling for Cell
References

cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2025-06-18T11:00:17.617Z

Reserved: 2025-06-18T10:57:27.382Z

Link: CVE-2022-49955

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Awaiting Analysis

Published: 2025-06-18T11:15:22.630

Modified: 2025-06-18T13:46:52.973

Link: CVE-2022-49955

cve-icon Redhat

Severity : Low

Publid Date: 2025-06-18T00:00:00Z

Links: CVE-2022-49955 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2025-06-23T08:45:29Z