In the Linux kernel, the following vulnerability has been resolved: x86/MCE: Always save CS register on AMD Zen IF Poison errors The Instruction Fetch (IF) units on current AMD Zen-based systems do not guarantee a synchronous #MC is delivered for poison consumption errors. Therefore, MCG_STATUS[EIPV|RIPV] will not be set. However, the microarchitecture does guarantee that the exception is delivered within the same context. In other words, the exact rIP is not known, but the context is known to not have changed. There is no architecturally-defined method to determine this behavior. The Code Segment (CS) register is always valid on such IF unit poison errors regardless of the value of MCG_STATUS[EIPV|RIPV]. Add a quirk to save the CS register for poison consumption from the IF unit banks. This is needed to properly determine the context of the error. Otherwise, the severity grading function will assume the context is IN_KERNEL due to the m->cs value being 0 (the initialized value). This leads to unnecessary kernel panics on data poison errors due to the kernel believing the poison consumption occurred in kernel context.
History

Fri, 19 Sep 2025 09:45:00 +0000

Type Values Removed Values Added
First Time appeared Linux
Linux linux Kernel
Vendors & Products Linux
Linux linux Kernel

Fri, 19 Sep 2025 00:15:00 +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


Thu, 18 Sep 2025 16:15:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: x86/MCE: Always save CS register on AMD Zen IF Poison errors The Instruction Fetch (IF) units on current AMD Zen-based systems do not guarantee a synchronous #MC is delivered for poison consumption errors. Therefore, MCG_STATUS[EIPV|RIPV] will not be set. However, the microarchitecture does guarantee that the exception is delivered within the same context. In other words, the exact rIP is not known, but the context is known to not have changed. There is no architecturally-defined method to determine this behavior. The Code Segment (CS) register is always valid on such IF unit poison errors regardless of the value of MCG_STATUS[EIPV|RIPV]. Add a quirk to save the CS register for poison consumption from the IF unit banks. This is needed to properly determine the context of the error. Otherwise, the severity grading function will assume the context is IN_KERNEL due to the m->cs value being 0 (the initialized value). This leads to unnecessary kernel panics on data poison errors due to the kernel believing the poison consumption occurred in kernel context.
Title x86/MCE: Always save CS register on AMD Zen IF Poison errors
References

cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published: 2025-09-18T16:04:16.501Z

Updated: 2025-09-18T16:04:16.501Z

Reserved: 2025-09-17T14:54:09.751Z

Link: CVE-2023-53438

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2025-09-18T16:15:47.967

Modified: 2025-09-18T16:15:47.967

Link: CVE-2023-53438

cve-icon Redhat

Severity : Moderate

Publid Date: 2025-09-18T00:00:00Z

Links: CVE-2023-53438 - Bugzilla