{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2021-47254","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2024-04-10T18:59:19.539Z","datePublished":"2024-05-21T14:19:49.475Z","dateUpdated":"2026-08-05T08:46:59.624Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T08:46:59.624Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ngfs2: Fix use-after-free in gfs2_glock_shrink_scan\n\nThe GLF_LRU flag is checked under lru_lock in gfs2_glock_remove_from_lru() to\nremove the glock from the lru list in __gfs2_glock_put().\n\nOn the shrink scan path, the same flag is cleared under lru_lock but because\nof cond_resched_lock(&lru_lock) in gfs2_dispose_glock_lru(), progress on the\nput side can be made without deleting the glock from the lru list.\n\nKeep GLF_LRU across the race window opened by cond_resched_lock(&lru_lock) to\nensure correct behavior on both sides - clear GLF_LRU after list_del under\nlru_lock."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The vulnerable path is the local GFS2 glock LRU shrinker and glock put path, reached via local filesystem operations and memory reclaim on a mounted GFS2 volume, not via network packet processing.\nAC:L - An attacker can induce both sides of the race by churning inode/iopen/flock glocks onto the LRU through ordinary file operations while concurrently creating memory pressure to force gfs2_glock_shrink_scan and dispose.\nPR:L - On a multi-user GFS2 deployment the filesystem is already mounted; an unprivileged local user with access to that mount can trigger glock get/put and reclaim without CAP_SYS_ADMIN.\nUI:N - No separate victim action is required; the attacker triggers the race through their own filesystem activity and memory allocation once GFS2 is available.\nS:U - This is a standard in-kernel use-after-free enabling privilege escalation within the same host security authority, not a VM/IOMMU/sandbox boundary crossing.\nC:H - Use-after-free of a slab-allocated gfs2_glock (aspace) object allows reclaim of attacker-controlled contents and arbitrary kernel memory disclosure primitives.\nI:H - The same UAF enables heap spraying and corruption of the freed glock object, providing arbitrary write / control-flow hijacking potential in the kernel.\nA:H - The bug manifests as a kernel use-after-free during list_del in gfs2_dispose_glock_lru (observed under KASAN), which can oops/panic and deny service."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/gfs2/glock.c"],"versions":[{"version":"6948c6bc17d666663a84c124b3176039e64a58f4","lessThan":"38ce329534500bf4ae71f81df6a37a406cf187b4","status":"affected","versionType":"git"},{"version":"b568ed385a18c0ddbe41862b69088b636550a04f","lessThan":"92869945cc5b78ee8a1ef90336fe070893e3458a","status":"affected","versionType":"git"},{"version":"762bb3528249604bc680a9df635e8995740176de","lessThan":"0364742decb0f02bc183404868b82896f7992595","status":"affected","versionType":"git"},{"version":"bac8520892812dada1ac93f27d96317470d24b1f","lessThan":"094bf5670e762afa243d2c41a5c4ab71c7447bf4","status":"affected","versionType":"git"},{"version":"7881ef3f33bb80f459ea6020d1e021fc524a6348","lessThan":"86fd5b27db743a0ce0cc245e3a34813b2aa6ec1d","status":"affected","versionType":"git"},{"version":"7881ef3f33bb80f459ea6020d1e021fc524a6348","lessThan":"a61156314b66456ab6a291ed5deba1ebd002ab3c","status":"affected","versionType":"git"},{"version":"7881ef3f33bb80f459ea6020d1e021fc524a6348","lessThan":"e87ef30fe73e7e10d2c85bdcc778dcec24dca553","status":"affected","versionType":"git"},{"version":"7881ef3f33bb80f459ea6020d1e021fc524a6348","lessThan":"1ab19c5de4c537ec0d9b21020395a5b5a6c059b2","status":"affected","versionType":"git"},{"version":"1e7a416fb765c9072479dc424780c0937ba99270","status":"affected","versionType":"git"},{"version":"dcbdbe13796ffa561510d2686a6318564e728bbd","status":"affected","versionType":"git"},{"version":"4.4.181","lessThan":"4.4.274","status":"affected","versionType":"semver"},{"version":"4.9.180","lessThan":"4.9.274","status":"affected","versionType":"semver"},{"version":"4.14.123","lessThan":"4.14.238","status":"affected","versionType":"semver"},{"version":"4.19.47","lessThan":"4.19.196","status":"affected","versionType":"semver"},{"version":"5.0.20","lessThan":"5.1","status":"affected","versionType":"semver"},{"version":"5.1.6","lessThan":"5.2","status":"affected","versionType":"semver"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/gfs2/glock.c"],"versions":[{"version":"5.2","status":"affected"},{"version":"0","lessThan":"5.2","status":"unaffected","versionType":"semver"},{"version":"4.4.274","lessThanOrEqual":"4.4.*","status":"unaffected","versionType":"semver"},{"version":"4.9.274","lessThanOrEqual":"4.9.*","status":"unaffected","versionType":"semver"},{"version":"4.14.238","lessThanOrEqual":"4.14.*","status":"unaffected","versionType":"semver"},{"version":"4.19.196","lessThanOrEqual":"4.19.*","status":"unaffected","versionType":"semver"},{"version":"5.4.127","lessThanOrEqual":"5.4.*","status":"unaffected","versionType":"semver"},{"version":"5.10.45","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.12.12","lessThanOrEqual":"5.12.*","status":"unaffected","versionType":"semver"},{"version":"5.13","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.4.181","versionEndExcluding":"4.4.274"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9.180","versionEndExcluding":"4.9.274"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14.123","versionEndExcluding":"4.14.238"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19.47","versionEndExcluding":"4.19.196"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.2","versionEndExcluding":"5.4.127"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.2","versionEndExcluding":"5.10.45"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.2","versionEndExcluding":"5.12.12"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.2","versionEndExcluding":"5.13"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.0.20"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.1.6"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/38ce329534500bf4ae71f81df6a37a406cf187b4"},{"url":"https://git.kernel.org/stable/c/92869945cc5b78ee8a1ef90336fe070893e3458a"},{"url":"https://git.kernel.org/stable/c/0364742decb0f02bc183404868b82896f7992595"},{"url":"https://git.kernel.org/stable/c/094bf5670e762afa243d2c41a5c4ab71c7447bf4"},{"url":"https://git.kernel.org/stable/c/86fd5b27db7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