System crash via raced negative optlen
Published Feb 23, 2021 · Updated Aug 3, 2024
Heap overflow in Linux Kernel versions higher than 5.2 allows local users to crash the system through the BPF getsockopt hook. In __cgroup_bpf_run_filter_getsockopt(), a previously checked user optlen can race to a negative value before copy_from_user uses it, producing an oversized copy when hardened usercopy is absent. Exploitation requires local BPF execution, four enabled kernel options, disabled CONFIG_HARDENED_USERCOPY, and a registered cgroup getsockopt hook; the record identifies privilege escalation as an additional possible consequence.
Summary
What happened
Heap overflow in Linux Kernel versions higher than 5.2 allows local users to crash the system through the BPF getsockopt hook. In __cgroup_bpf_run_filter_getsockopt(), a previously checked user optlen can race to a negative value before copy_from_user uses it, producing an oversized copy when hardened usercopy is absent. Exploitation requires local BPF execution, four enabled kernel options, disabled CONFIG_HARDENED_USERCOPY, and a registered cgroup getsockopt hook; the record identifies privilege escalation as an additional possible consequence.
The record
- CVE
- CVE-2021-20194
- Published
- Feb 23, 2021
- Updated
- Aug 3, 2024
- Vendor
- The Linux Kernel Organization
- Product
- Linux Kernel
- Classifications
- CWE-20, CWE-787, T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Feb 23, 2021CVE publishedPublication date reported by the CVE source.
- Aug 3, 2024Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=kernel 5.2 and higher.
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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