# CVE-2022-49164: linux: In the Linux kernel, the following vulnerability has been resolved:  powerpc/tm: Fix more userspace r13 corruption  C...

CVE-2022-49164 is fixed in linux on 1 platform, first by DEBIAN-CVE-2022-49164, released February 26, 2025. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2022-49164
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0027
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Feb 26, 2025

## Description

In the Linux kernel, the following vulnerability has been resolved:  powerpc/tm: Fix more userspace r13 corruption  Commit cf13435b730a ("powerpc/tm: Fix userspace r13 corruption") fixes a problem in treclaim where a SLB miss can occur on the thread_struct->ckpt_regs while SCRATCH0 is live with the saved user r13 value, clobbering it with the kernel r13 and ultimately resulting in kernel r13 being stored in ckpt_regs.  There is an equivalent problem in trechkpt where the user r13 value is loaded into r13 from chkpt_regs to be recheckpointed, but a SLB miss could occur on ckpt_regs accesses after that, which will result in r13 being clobbered with a kernel value and that will get recheckpointed and then restored to user registers.  The same memory page is accessed right before this critical window where a SLB miss could cause corruption, so hitting the bug requires the SLB entry be removed within a small window of instructions, which is possible if a SLB related MCE hits there. PAPR also permits the hypervisor to discard this SLB entry (because slb_shadow->persistent is only set to SLB_NUM_BOLTED) although it's not known whether any implementations would do this (KVM does not). So this is an extremely unlikely bug, only found by inspection.  Fix this by also storing user r13 in a temporary location on the kernel stack and don't change the r13 register from kernel r13 until the RI=0 critical section that does not fault.  The SCRATCH0 change is not strictly part of the fix, it's only used in the RI=0 section so it does not have the same problem as the previous SCRATCH0 bug.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 5.17.3-1 | [DEBIAN-CVE-2022-49164](https://patchblox.com/security/data/fix/linux/debian-cve-2022-49164.md) | Feb 26, 2025 |
| Linux | linux Debian 13.5 (trixie) | 5.17.3-1 | [DEBIAN-CVE-2022-49164](https://patchblox.com/security/data/fix/linux/debian-cve-2022-49164.md) | Feb 26, 2025 |
| Linux | linux Debian 14 | 5.17.3-1 | [DEBIAN-CVE-2022-49164](https://patchblox.com/security/data/fix/linux/debian-cve-2022-49164.md) | Feb 26, 2025 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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