CVE-2022-49955: 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…

PriorityP420medium5.5CVSS 3.1

AVLACLPRLUINSUCNINAH

EPSS

0.18%

7.6th percentile

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 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.

Affected

18 ranges

Vendor	Product	Version range	Fixed in
debian	linux	< linux 6.0.2-1 (bookworm)	linux 6.0.2-1 (bookworm)
linux	linux	—	—
linux	linux	—	—
linux	linux	—	—
linux	linux	—	—
linux	linux	>= 5.15.46 < 5.16	5.16
linux	linux	>= 5.17.14 < 5.18	5.18
linux	linux	>= 5.18.3 < 5.19	5.19
linux	linux	>= b6b1c3ce06ca438eb24e0f45bf0e63ecad0369f5 < 8b08d4f97233d8e58fff2fd9d5f86397a49733c5	8b08d4f97233d8e58fff2fd9d5f86397a49733c5
linux	linux	>= b6b1c3ce06ca438eb24e0f45bf0e63ecad0369f5 < 91926d8b7e71aaf5f84f0cf208fc5a8b7a761050	91926d8b7e71aaf5f84f0cf208fc5a8b7a761050
linux	linux_kernel	—	—
linux	linux_kernel	>= 0 < 6.0.2-1	6.0.2-1
linux	linux_kernel	>= 0 < 6.0.2-1	6.0.2-1
linux	linux_kernel	>= 0 < 6.0.2-1	6.0.2-1
linux	linux_kernel	>= 5.15.46 < 5.16	5.16
linux	linux_kernel	>= 5.17.14 < 5.18	5.18
linux	linux_kernel	>= 5.18.3 < 5.19.8	5.19.8
msrc	cbl2_kernel_5.15.186.1-1_on_cbl_mariner_2.0	—	—

CVSS provenance

nvdv3.15.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

osv5.5MEDIUM

vendor_debian5.5MEDIUM

vendor_msrc5.5MEDIUM

vendor_redhat5.5MEDIUM

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