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CVE-2022-49955

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

Medium5.5EPSS 0.21%
Published
Updated
Reserved
Assigned by
Linux

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.

Timeline

  1. ID reserved

    By Linux

  2. Published

  3. · 17 months later

    Record updated

Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.

Scores

CVSS scores of CVE-2022-49955, by who scored it
Scored byCVSSScoreVector
NVDNVD · Analyzed3.1Medium5.5CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS (exploitation in 30 days)
0.21% · top 89% of all CVEs (7 Nov 2026)
CISA SSVC
Exploitation: none · Automatable: no · Technical impact: partial
Loading the EPSS history…

The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.5.

Weakness

Affected products

  • Linux · Linux

    • affected b6b1c3ce06ca438eb24e0f45bf0e63ecad0369f5 – < 8b08d4f97233d8e58fff2fd9d5f86397a49733c5
    • affected b6b1c3ce06ca438eb24e0f45bf0e63ecad0369f5 – < 91926d8b7e71aaf5f84f0cf208fc5a8b7a761050
    • affected 5ca40fcf0da0ce2b5bc44e7d8b036535955f2e3d
    • affected 5f4367448f6817c8a0e94dc9736ed84fa8eee4a3
    • affected c9c41f0273826a13ac93124e66a4ff45df281ba0
    • affected 5.15.46 – < 5.16
    • affected 5.17.14 – < 5.18
    • affected 5.18.3 – < 5.19

  • Linux · Linux

    • affected 5.19
    • unaffected < 5.19
    • unaffected 5.19.8 – ≤ 5.19.*
    • unaffected 6.0 – ≤ *

References (2)

Sources

The same CVE in the primary databases and aggregators, to check against.

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Record last updated .