Local privilege escalation via glock LRU race
Published May 21, 2024 · Updated Aug 5, 2026
Use-after-free in the Linux GFS2 glock LRU shrinker allows local users to corrupt kernel memory through filesystem activity. gfs2_dispose_glock_lru clears GLF_LRU before list deletion, and a rescheduling window lets the put path free a glock that remains on the LRU list. Exploitation requires access to a mounted GFS2 volume and concurrent memory pressure; successful corruption grants kernel privileges or crashes the host.
Summary
What happened
Use-after-free in the Linux GFS2 glock LRU shrinker allows local users to corrupt kernel memory through filesystem activity. gfs2_dispose_glock_lru clears GLF_LRU before list deletion, and a rescheduling window lets the put path free a glock that remains on the LRU list. Exploitation requires access to a mounted GFS2 volume and concurrent memory pressure; successful corruption grants kernel privileges or crashes the host.
The record
- CVE
- CVE-2021-47254
- Published
- May 21, 2024
- Updated
- Aug 5, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- May 21, 2024CVE publishedPublication date reported by the CVE source.
- Aug 5, 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=1e7a416fb765c9072479dc424780c0937ba99270
- Affected versionversion=4.14.123 <4.14.238
- Affected versionversion=4.19.47 <4.19.196
- Affected versionversion=4.4.181 <4.4.274
- Affected versionversion=4.9.180 <4.9.274
- Affected versionversion=5.0.20 <5.1
- Affected versionversion=5.1.6 <5.2
- Affected versionversion=5.2
- Affected versionversion=6948c6bc17d666663a84c124b3176039e64a58f4 <38ce329534500bf4ae71f81df6a37a406cf187b4
- Affected versionversion=762bb3528249604bc680a9df635e8995740176de <0364742decb0f02bc183404868b82896f7992595
- Affected versionversion=7881ef3f33bb80f459ea6020d1e021fc524a6348 <1ab19c5de4c537ec0d9b21020395a5b5a6c059b2
- Affected versionversion=7881ef3f33bb80f459ea6020d1e021fc524a6348 <86fd5b27db743a0ce0cc245e3a34813b2aa6ec1d
- Affected versionversion=7881ef3f33bb80f459ea6020d1e021fc524a6348 <a61156314b66456ab6a291ed5deba1ebd002ab3c
- Affected versionversion=7881ef3f33bb80f459ea6020d1e021fc524a6348 <e87ef30fe73e7e10d2c85bdcc778dcec24dca553
- Affected versionversion=b568ed385a18c0ddbe41862b69088b636550a04f <92869945cc5b78ee8a1ef90336fe070893e3458a
- Affected versionversion=bac8520892812dada1ac93f27d96317470d24b1f <094bf5670e762afa243d2c41a5c4ab71c7447bf4
- Affected versionversion=dcbdbe13796ffa561510d2686a6318564e728bbd
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What is affected?
Published CVSS scores
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Attacks
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