Local denial of service via direct-I/O deadlock
Published Feb 26, 2025 · Updated May 23, 2026
Improper locking in Linux kernel Btrfs allows local users to hang filesystem work through concurrent direct I/O writes under low space. Overlapping writes retain different file-range locks while space reservation waits on asynchronous reclaim, which in turn waits for an ordered extent blocked by those locks. Exploitation requires access to write within an existing multi-extent Btrfs file while available data space is low; the resulting cycle blocks the participating writes and kernel workqueue tasks.
Summary
What happened
Improper locking in Linux kernel Btrfs allows local users to hang filesystem work through concurrent direct I/O writes under low space. Overlapping writes retain different file-range locks while space reservation waits on asynchronous reclaim, which in turn waits for an ordered extent blocked by those locks. Exploitation requires access to write within an existing multi-extent Btrfs file while available data space is low; the resulting cycle blocks the participating writes and kernel workqueue tasks.
The record
- CVE
- CVE-2022-49547
- Published
- Feb 26, 2025
- Updated
- May 23, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- CWE-667, T1499
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Feb 26, 2025CVE publishedPublication date reported by the CVE source.
- May 23, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=5.15.27 <5.16
- Affected versionversion=5.16.13 <5.17
- Affected versionversion=5.17
- Affected versionversion=5afd80c393f4e87451f14eefb7f2f24daf434e06
- Affected versionversion=96f1be29492d9e2fb97bb27f824478ab8cd3ab86
- Affected versionversion=f0bfa76a11e93d0fe2c896fcb566568c5e8b5d3f <cfae6f765b3c40882ee90dae8fbf9325c8de9c35
- Affected versionversion=f0bfa76a11e93d0fe2c896fcb566568c5e8b5d3f <f5585f4f0ef5b17026bbd60fbff6fcc91b99d5bf
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
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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