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.
Metrics
Affected Vendors & Products
References
History
Fri, 19 Sep 2025 09:45:00 +0000
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Linux
Linux linux Kernel |
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Linux
Linux linux Kernel |
Fri, 19 Sep 2025 00:15:00 +0000
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| Metrics |
threat_severity
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cvssV3_1
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Thu, 18 Sep 2025 16:15:00 +0000
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| 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 |
|
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
No data.
Status : Received
Published: 2025-09-18T16:15:47.967
Modified: 2025-09-18T16:15:47.967
Link: CVE-2023-53438