Local information disclosure via repeated BPF test runs
Published Mar 16, 2022 · Updated Aug 4, 2024
Out-of-bounds read in the Android kernel allows local users with system privileges to disclose kernel memory through BPF test runs. In bpf_prog_test_run_skb in net/bpf/test_run.c, repeated execution can exhaust packet headroom before an Ethernet header is pushed and copied to userspace. Access requires CAP_SYS_ADMIN in the initial user namespace, and no user interaction is required; the bounded impact is disclosure of adjacent kernel memory.
Summary
What happened
Out-of-bounds read in the Android kernel allows local users with system privileges to disclose kernel memory through BPF test runs. In bpf_prog_test_run_skb in net/bpf/test_run.c, repeated execution can exhaust packet headroom before an Ethernet header is pushed and copied to userspace. Access requires CAP_SYS_ADMIN in the initial user namespace, and no user interaction is required; the bounded impact is disclosure of adjacent kernel memory.
The record
- CVE
- CVE-2021-39711
- Published
- Mar 16, 2022
- Updated
- Aug 4, 2024
- Vendor
- Google Cloud
- Product
- Android
- Classifications
- CWE-125, T1533
- Attack vector
- local
- Privileges
- admin
Timeline
How it unfolded
- Mar 16, 2022CVE publishedPublication date reported by the CVE source.
- Aug 4, 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=Android kernel
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- syzkaller bpf_prog_test_run_skb reproducerproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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