CVE-2022-49955

Source
https://nvd.nist.gov/vuln/detail/CVE-2022-49955
Import Source
https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2022-49955.json
JSON Data
https://api.test.osv.dev/v1/vulns/CVE-2022-49955
Downstream
Published
2025-06-18T11:15:22Z
Modified
2025-06-18T16:01:33Z
Summary
[none]
Details

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 PAGESIZE=64K MMU=Hash SMP NRCPUS=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) .rtascall+0x224/0x320 .rtasgetboottime+0x70/0x150 .readpersistentclock64+0x114/0x140 .readpersistentwallandbootoffset+0x24/0x80 .timekeepinginit+0x40/0x29c .startkernel+0x674/0x8f0 starthere_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.

References

Affected packages

Debian:12 / linux

Package

Name
linux
Purl
pkg:deb/debian/linux?arch=source

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
6.0.2-1

Ecosystem specific

{
    "urgency": "not yet assigned"
}

Debian:13 / linux

Package

Name
linux
Purl
pkg:deb/debian/linux?arch=source

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
6.0.2-1

Ecosystem specific

{
    "urgency": "not yet assigned"
}