Floating-point state loss via stale SD bit
Published Jul 18, 2022 · Updated Aug 3, 2024
Incorrect state tracking in OpenHW Group CVA6 allows local users to trigger floating-point register data loss during a context switch. After a floating-point instruction sets mstatus.fs to Dirty, the RTL leaves the read-only mstatus.sd summary bit clear instead of updating it immediately. Code executing on an affected core must first dirty floating-point state; a subsequent context switch can then omit those register contents.
Summary
What happened
Incorrect state tracking in OpenHW Group CVA6 allows local users to trigger floating-point register data loss during a context switch. After a floating-point instruction sets mstatus.fs to Dirty, the RTL leaves the read-only mstatus.sd summary bit clear instead of updating it immediately. Code executing on an affected core must first dirty floating-point state; a subsequent context switch can then omit those register contents.
The record
- CVE
- CVE-2022-34635
- Published
- Jul 18, 2022
- Updated
- Aug 3, 2024
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-1199
- Attack vector
- local
- Privileges
- Unavailable
Timeline
How it unfolded
- Jul 18, 2022CVE publishedPublication date reported by the CVE source.
- Aug 3, 2024Record updatedLatest update available in the CVE record.
Exploitability
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What is affected?
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Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
- sd bit does not update immediately reproduction caseproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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