Kernel-memory disclosure via speculative pointer underflow
Published Mar 20, 2021 · Updated Aug 4, 2024
An off-by-one error in the Linux kernel before 5.11.8 allows local users to obtain kernel-memory contents through a speculative side channel. The retrieve_ptr_limit function calculates a valid stack or map-value area one byte short, causing mask creation to underflow and fail to constrain speculative pointer arithmetic. Exploitation requires local access and the ability to load BPF programs, typically CAP_SYS_ADMIN or root when unprivileged BPF is disabled.
Summary
What happened
An off-by-one error in the Linux kernel before 5.11.8 allows local users to obtain kernel-memory contents through a speculative side channel. The retrieve_ptr_limit function calculates a valid stack or map-value area one byte short, causing mask creation to underflow and fail to constrain speculative pointer arithmetic. Exploitation requires local access and the ability to load BPF programs, typically CAP_SYS_ADMIN or root when unprivileged BPF is disabled.
The record
- CVE
- CVE-2020-27171
- Published
- Mar 20, 2021
- Updated
- Aug 4, 2024
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-193
- Attack vector
- local
- Privileges
- admin
Timeline
How it unfolded
- Mar 20, 2021CVE publishedPublication date reported by the CVE source.
- Aug 4, 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
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Public exploit references
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Technologies
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