{"api_version":"1","generated_at":"2026-10-21T16:51:52+00:00","cve":"CVE-2025-21722","urls":{"html":"https://cve.report/CVE-2025-21722","api":"https://cve.report/api/cve/CVE-2025-21722.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2025-21722","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2025-21722"},"summary":{"title":"nilfs2: do not force clear folio if buffer is referenced","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnilfs2: do not force clear folio if buffer is referenced\n\nPatch series \"nilfs2: protect busy buffer heads from being force-cleared\".\n\nThis series fixes the buffer head state inconsistency issues reported by\nsyzbot that occurs when the filesystem is corrupted and falls back to\nread-only, and the associated buffer head use-after-free issue.\n\n\nThis patch (of 2):\n\nSyzbot has reported that after nilfs2 detects filesystem corruption and\nfalls back to read-only, inconsistencies in the buffer state may occur.\n\nOne of the inconsistencies is that when nilfs2 calls mark_buffer_dirty()\nto set a data or metadata buffer as dirty, but it detects that the buffer\nis not in the uptodate state:\n\n WARNING: CPU: 0 PID: 6049 at fs/buffer.c:1177 mark_buffer_dirty+0x2e5/0x520\n  fs/buffer.c:1177\n ...\n Call Trace:\n  <TASK>\n  nilfs_palloc_commit_alloc_entry+0x4b/0x160 fs/nilfs2/alloc.c:598\n  nilfs_ifile_create_inode+0x1dd/0x3a0 fs/nilfs2/ifile.c:73\n  nilfs_new_inode+0x254/0x830 fs/nilfs2/inode.c:344\n  nilfs_mkdir+0x10d/0x340 fs/nilfs2/namei.c:218\n  vfs_mkdir+0x2f9/0x4f0 fs/namei.c:4257\n  do_mkdirat+0x264/0x3a0 fs/namei.c:4280\n  __do_sys_mkdirat fs/namei.c:4295 [inline]\n  __se_sys_mkdirat fs/namei.c:4293 [inline]\n  __x64_sys_mkdirat+0x87/0xa0 fs/namei.c:4293\n  do_syscall_x64 arch/x86/entry/common.c:52 [inline]\n  do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83\n  entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nThe other is when nilfs_btree_propagate(), which propagates the dirty\nstate to the ancestor nodes of a b-tree that point to a dirty buffer,\ndetects that the origin buffer is not dirty, even though it should be:\n\n WARNING: CPU: 0 PID: 5245 at fs/nilfs2/btree.c:2089\n  nilfs_btree_propagate+0xc79/0xdf0 fs/nilfs2/btree.c:2089\n ...\n Call Trace:\n  <TASK>\n  nilfs_bmap_propagate+0x75/0x120 fs/nilfs2/bmap.c:345\n  nilfs_collect_file_data+0x4d/0xd0 fs/nilfs2/segment.c:587\n  nilfs_segctor_apply_buffers+0x184/0x340 fs/nilfs2/segment.c:1006\n  nilfs_segctor_scan_file+0x28c/0xa50 fs/nilfs2/segment.c:1045\n  nilfs_segctor_collect_blocks fs/nilfs2/segment.c:1216 [inline]\n  nilfs_segctor_collect fs/nilfs2/segment.c:1540 [inline]\n  nilfs_segctor_do_construct+0x1c28/0x6b90 fs/nilfs2/segment.c:2115\n  nilfs_segctor_construct+0x181/0x6b0 fs/nilfs2/segment.c:2479\n  nilfs_segctor_thread_construct fs/nilfs2/segment.c:2587 [inline]\n  nilfs_segctor_thread+0x69e/0xe80 fs/nilfs2/segment.c:2701\n  kthread+0x2f0/0x390 kernel/kthread.c:389\n  ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147\n  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244\n  </TASK>\n\nBoth of these issues are caused by the callbacks that handle the\npage/folio write requests, forcibly clear various states, including the\nworking state of the buffers they hold, at unexpected times when they\ndetect read-only fallback.\n\nFix these issues by checking if the buffer is referenced before clearing\nthe page/folio state, and skipping the clear if it is.","state":"PUBLISHED","assigner":"Linux","published_at":"2025-02-27 02:15:15","updated_at":"2026-10-21 13:17:55"},"problem_types":["CWE-416","CWE-416 CWE-416 Use After Free"],"metrics":[{"version":"3.1","source":"ADP","type":"DECLARED","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"attackComplexity":"LOW","attackVector":"LOCAL","availabilityImpact":"HIGH","baseScore":7.8,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"LOW","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}},{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"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","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","type":"Secondary","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"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","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html","name":"https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html","refsource":"af854a3a-2127-422b-91ae-364da2661108","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/4d042811c72f71be7c14726db2c72b67025a7cb5","name":"https://git.kernel.org/stable/c/4d042811c72f71be7c14726db2c72b67025a7cb5","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/f51ff43c4c5a6c8e72d0aca89e4d5e688938412f","name":"https://git.kernel.org/stable/c/f51ff43c4c5a6c8e72d0aca89e4d5e688938412f","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/1098bb8d52419d262a3358d099a1598a920b730f","name":"https://git.kernel.org/stable/c/1098bb8d52419d262a3358d099a1598a920b730f","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/ca76bb226bf47ff04c782cacbd299f12ddee1ec1","name":"https://git.kernel.org/stable/c/ca76bb226bf47ff04c782cacbd299f12ddee1ec1","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/8458c686d50a804611b97038dd6e75a474ac2221","name":"https://git.kernel.org/stable/c/8458c686d50a804611b97038dd6e75a474ac2221","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/19296737024cd220a1d6590bf4c092bca8c99497","name":"https://git.kernel.org/stable/c/19296737024cd220a1d6590bf4c092bca8c99497","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/7d0544bacc11d6aa26ecd7debf9353193c7a3328","name":"https://git.kernel.org/stable/c/7d0544bacc11d6aa26ecd7debf9353193c7a3328","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html","name":"https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html","refsource":"af854a3a-2127-422b-91ae-364da2661108","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/557ccf5e49f1fb848a29698585bcab2e50a597ef","name":"https://git.kernel.org/stable/c/557ccf5e49f1fb848a29698585bcab2e50a597ef","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2025-21722","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2025-21722","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 8c26c4e2694a163d525976e804d81cd955bbb40c 7d0544bacc11d6aa26ecd7debf9353193c7a3328 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 8c26c4e2694a163d525976e804d81cd955bbb40c 4d042811c72f71be7c14726db2c72b67025a7cb5 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 8c26c4e2694a163d525976e804d81cd955bbb40c f51ff43c4c5a6c8e72d0aca89e4d5e688938412f git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 8c26c4e2694a163d525976e804d81cd955bbb40c 19296737024cd220a1d6590bf4c092bca8c99497 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 8c26c4e2694a163d525976e804d81cd955bbb40c 8458c686d50a804611b97038dd6e75a474ac2221 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 8c26c4e2694a163d525976e804d81cd955bbb40c 1098bb8d52419d262a3358d099a1598a920b730f git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 8c26c4e2694a163d525976e804d81cd955bbb40c 557ccf5e49f1fb848a29698585bcab2e50a597ef git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 8c26c4e2694a163d525976e804d81cd955bbb40c ca76bb226bf47ff04c782cacbd299f12ddee1ec1 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3.10","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 3.10 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.4.291 5.4.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.10.235 5.10.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.15.179 5.15.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.1.129 6.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.160 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.13 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.13.2 6.13.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.14 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[{"cve_year":"2025","cve_id":"21722","vulnerable":"1","versionEndIncluding":"","cpe1":"cpe","cpe2":"2.3","cpe3":"o","cpe4":"linux","cpe5":"linux_kernel","cpe6":"*","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"*","cpe11":"*","cpe12":"*","cpe13":"*"}],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"adp":[{"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"LOCAL","availabilityImpact":"HIGH","baseScore":7.8,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"LOW","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}},{"other":{"content":{"id":"CVE-2025-21722","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","timestamp":"2025-02-27T18:14:37.739187Z","version":"2.0.3"},"type":"ssvc"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-416","description":"CWE-416 Use After Free","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2025-02-27T18:22:30.078Z","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP"},"title":"CISA ADP Vulnrichment"},{"providerMetadata":{"dateUpdated":"2025-11-03T19:36:21.865Z","orgId":"af854a3a-2127-422b-91ae-364da2661108","shortName":"CVE"},"references":[{"url":"https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html"},{"url":"https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html"}],"title":"CVE Program Container"}],"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["fs/nilfs2/page.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"7d0544bacc11d6aa26ecd7debf9353193c7a3328","status":"affected","version":"8c26c4e2694a163d525976e804d81cd955bbb40c","versionType":"git"},{"lessThan":"4d042811c72f71be7c14726db2c72b67025a7cb5","status":"affected","version":"8c26c4e2694a163d525976e804d81cd955bbb40c","versionType":"git"},{"lessThan":"f51ff43c4c5a6c8e72d0aca89e4d5e688938412f","status":"affected","version":"8c26c4e2694a163d525976e804d81cd955bbb40c","versionType":"git"},{"lessThan":"19296737024cd220a1d6590bf4c092bca8c99497","status":"affected","version":"8c26c4e2694a163d525976e804d81cd955bbb40c","versionType":"git"},{"lessThan":"8458c686d50a804611b97038dd6e75a474ac2221","status":"affected","version":"8c26c4e2694a163d525976e804d81cd955bbb40c","versionType":"git"},{"lessThan":"1098bb8d52419d262a3358d099a1598a920b730f","status":"affected","version":"8c26c4e2694a163d525976e804d81cd955bbb40c","versionType":"git"},{"lessThan":"557ccf5e49f1fb848a29698585bcab2e50a597ef","status":"affected","version":"8c26c4e2694a163d525976e804d81cd955bbb40c","versionType":"git"},{"lessThan":"ca76bb226bf47ff04c782cacbd299f12ddee1ec1","status":"affected","version":"8c26c4e2694a163d525976e804d81cd955bbb40c","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/nilfs2/page.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"3.10"},{"lessThan":"3.10","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"5.4.*","status":"unaffected","version":"5.4.291","versionType":"semver"},{"lessThanOrEqual":"5.10.*","status":"unaffected","version":"5.10.235","versionType":"semver"},{"lessThanOrEqual":"5.15.*","status":"unaffected","version":"5.15.179","versionType":"semver"},{"lessThanOrEqual":"6.1.*","status":"unaffected","version":"6.1.129","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.160","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.13","versionType":"semver"},{"lessThanOrEqual":"6.13.*","status":"unaffected","version":"6.13.2","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"6.14","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.4.291","versionStartIncluding":"3.10","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.10.235","versionStartIncluding":"3.10","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.15.179","versionStartIncluding":"3.10","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.1.129","versionStartIncluding":"3.10","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.160","versionStartIncluding":"3.10","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.13","versionStartIncluding":"3.10","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.13.2","versionStartIncluding":"3.10","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.14","versionStartIncluding":"3.10","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnilfs2: do not force clear folio if buffer is referenced\n\nPatch series \"nilfs2: protect busy buffer heads from being force-cleared\".\n\nThis series fixes the buffer head state inconsistency issues reported by\nsyzbot that occurs when the filesystem is corrupted and falls back to\nread-only, and the associated buffer head use-after-free issue.\n\n\nThis patch (of 2):\n\nSyzbot has reported that after nilfs2 detects filesystem corruption and\nfalls back to read-only, inconsistencies in the buffer state may occur.\n\nOne of the inconsistencies is that when nilfs2 calls mark_buffer_dirty()\nto set a data or metadata buffer as dirty, but it detects that the buffer\nis not in the uptodate state:\n\n WARNING: CPU: 0 PID: 6049 at fs/buffer.c:1177 mark_buffer_dirty+0x2e5/0x520\n  fs/buffer.c:1177\n ...\n Call Trace:\n  <TASK>\n  nilfs_palloc_commit_alloc_entry+0x4b/0x160 fs/nilfs2/alloc.c:598\n  nilfs_ifile_create_inode+0x1dd/0x3a0 fs/nilfs2/ifile.c:73\n  nilfs_new_inode+0x254/0x830 fs/nilfs2/inode.c:344\n  nilfs_mkdir+0x10d/0x340 fs/nilfs2/namei.c:218\n  vfs_mkdir+0x2f9/0x4f0 fs/namei.c:4257\n  do_mkdirat+0x264/0x3a0 fs/namei.c:4280\n  __do_sys_mkdirat fs/namei.c:4295 [inline]\n  __se_sys_mkdirat fs/namei.c:4293 [inline]\n  __x64_sys_mkdirat+0x87/0xa0 fs/namei.c:4293\n  do_syscall_x64 arch/x86/entry/common.c:52 [inline]\n  do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83\n  entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nThe other is when nilfs_btree_propagate(), which propagates the dirty\nstate to the ancestor nodes of a b-tree that point to a dirty buffer,\ndetects that the origin buffer is not dirty, even though it should be:\n\n WARNING: CPU: 0 PID: 5245 at fs/nilfs2/btree.c:2089\n  nilfs_btree_propagate+0xc79/0xdf0 fs/nilfs2/btree.c:2089\n ...\n Call Trace:\n  <TASK>\n  nilfs_bmap_propagate+0x75/0x120 fs/nilfs2/bmap.c:345\n  nilfs_collect_file_data+0x4d/0xd0 fs/nilfs2/segment.c:587\n  nilfs_segctor_apply_buffers+0x184/0x340 fs/nilfs2/segment.c:1006\n  nilfs_segctor_scan_file+0x28c/0xa50 fs/nilfs2/segment.c:1045\n  nilfs_segctor_collect_blocks fs/nilfs2/segment.c:1216 [inline]\n  nilfs_segctor_collect fs/nilfs2/segment.c:1540 [inline]\n  nilfs_segctor_do_construct+0x1c28/0x6b90 fs/nilfs2/segment.c:2115\n  nilfs_segctor_construct+0x181/0x6b0 fs/nilfs2/segment.c:2479\n  nilfs_segctor_thread_construct fs/nilfs2/segment.c:2587 [inline]\n  nilfs_segctor_thread+0x69e/0xe80 fs/nilfs2/segment.c:2701\n  kthread+0x2f0/0x390 kernel/kthread.c:389\n  ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147\n  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244\n  </TASK>\n\nBoth of these issues are caused by the callbacks that handle the\npage/folio write requests, forcibly clear various states, including the\nworking state of the buffers they hold, at unexpected times when they\ndetect read-only fallback.\n\nFix these issues by checking if the buffer is referenced before clearing\nthe page/folio state, and skipping the clear if it is."}],"metrics":[{"cvssV3_1":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:L - The vulnerable code is reached only through local VFS activity on a mounted nilfs2 volume — write/mkdir/fsync/sync syscalls plus kernel writeback on that mount. There is no network consumer of fs/nilfs2/page.c.\nAC:L - The attacker supplies the corrupted image that makes the read-only fallback deterministic, and drives both sides of the race themselves (sync/fsync or memory pressure to force writeback, concurrently with a mkdir/write loop holding buffer references); syzbot reproduced it reliably and the fix carries a Tested-by.\nPR:L - Once the volume is mounted — automounted removable media, a shared multi-user nilfs2 mount, or a loop image — an ordinary unprivileged user reaches the force-clear through plain VFS syscalls, with no capability check anywhere on the path to nilfs_clear_folio_dirty().\nUI:N - With the filesystem already mounted (udisks2 automount or an existing shared mount), the attacker triggers corruption detection, writeback, and the concurrent buffer access entirely on their own; no victim action is required.\nS:U - The corruption occurs in kernel buffer-head and page-cache structures on the same host under the same security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - Clearing BH_Dirty removes the buffer_busy() protection so try_to_free_buffers() frees the bh ring while nilfs_lookup_dirty_node_buffers() is still dereferencing it, giving a use-after-free read of reallocated slab contents; force-clearing BH_Uptodate/folio uptodate additionally lets stale page-cache data be treated as valid.\nI:H - The same UAF window has the segment constructor perform get_bh() and list_add_tail() into freed buffer_head memory — an attacker-groomable write primitive — and the force-clear silently discards in-flight ifile/DAT metadata updates and drops block mappings, corrupting on-disk filesystem state.\nA:H - The bug produces kernel WARNs in mark_buffer_dirty() and nilfs_btree_propagate() (panic with panic_on_warn), oopses from the use-after-free, and leaves the segment-constructor kthread walking a corrupted buffer list, hanging all further filesystem activity."}]}],"providerMetadata":{"dateUpdated":"2026-10-21T12:35:56.141Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/7d0544bacc11d6aa26ecd7debf9353193c7a3328"},{"url":"https://git.kernel.org/stable/c/4d042811c72f71be7c14726db2c72b67025a7cb5"},{"url":"https://git.kernel.org/stable/c/f51ff43c4c5a6c8e72d0aca89e4d5e688938412f"},{"url":"https://git.kernel.org/stable/c/19296737024cd220a1d6590bf4c092bca8c99497"},{"url":"https://git.kernel.org/stable/c/8458c686d50a804611b97038dd6e75a474ac2221"},{"url":"https://git.kernel.org/stable/c/1098bb8d52419d262a3358d099a1598a920b730f"},{"url":"https://git.kernel.org/stable/c/557ccf5e49f1fb848a29698585bcab2e50a597ef"},{"url":"https://git.kernel.org/stable/c/ca76bb226bf47ff04c782cacbd299f12ddee1ec1"}],"title":"nilfs2: do not force clear folio if buffer is referenced","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2025-21722","datePublished":"2025-02-27T02:07:30.387Z","dateReserved":"2024-12-29T08:45:45.753Z","dateUpdated":"2026-10-21T12:35:56.141Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2025-02-27 02:15:15","lastModifiedDate":"2026-10-21 13:17:55","problem_types":["CWE-416","CWE-416 CWE-416 Use After 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do not force clear folio if buffer is referenced","CVE":"CVE-2025-21722","Year":"2025"},"notes":[{"CveYear":"2025","CveId":"21722","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nnilfs2: do not force clear folio if buffer is referenced\n\nPatch series \"nilfs2: protect busy buffer heads from being force-cleared\".\n\nThis series fixes the buffer head state inconsistency issues reported by\nsyzbot that occurs when the filesystem is corrupted and falls back to\nread-only, and the associated buffer head use-after-free issue.\n\n\nThis patch (of 2):\n\nSyzbot has reported that after nilfs2 detects filesystem corruption and\nfalls back to read-only, inconsistencies in the buffer state may occur.\n\nOne of the inconsistencies is that when nilfs2 calls mark_buffer_dirty()\nto set a data or metadata buffer as dirty, but it detects that the buffer\nis not in the uptodate state:\n\n WARNING: CPU: 0 PID: 6049 at fs/buffer.c:1177 mark_buffer_dirty+0x2e5/0x520\n  fs/buffer.c:1177\n ...\n Call Trace:\n  <TASK>\n  nilfs_palloc_commit_alloc_entry+0x4b/0x160 fs/nilfs2/alloc.c:598\n  nilfs_ifile_create_inode+0x1dd/0x3a0 fs/nilfs2/ifile.c:73\n  nilfs_new_inode+0x254/0x830 fs/nilfs2/inode.c:344\n  nilfs_mkdir+0x10d/0x340 fs/nilfs2/namei.c:218\n  vfs_mkdir+0x2f9/0x4f0 fs/namei.c:4257\n  do_mkdirat+0x264/0x3a0 fs/namei.c:4280\n  __do_sys_mkdirat fs/namei.c:4295 [inline]\n  __se_sys_mkdirat fs/namei.c:4293 [inline]\n  __x64_sys_mkdirat+0x87/0xa0 fs/namei.c:4293\n  do_syscall_x64 arch/x86/entry/common.c:52 [inline]\n  do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83\n  entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nThe other is when nilfs_btree_propagate(), which propagates the dirty\nstate to the ancestor nodes of a b-tree that point to a dirty buffer,\ndetects that the origin buffer is not dirty, even though it should be:\n\n WARNING: CPU: 0 PID: 5245 at fs/nilfs2/btree.c:2089\n  nilfs_btree_propagate+0xc79/0xdf0 fs/nilfs2/btree.c:2089\n ...\n Call Trace:\n  <TASK>\n  nilfs_bmap_propagate+0x75/0x120 fs/nilfs2/bmap.c:345\n  nilfs_collect_file_data+0x4d/0xd0 fs/nilfs2/segment.c:587\n  nilfs_segctor_apply_buffers+0x184/0x340 fs/nilfs2/segment.c:1006\n  nilfs_segctor_scan_file+0x28c/0xa50 fs/nilfs2/segment.c:1045\n  nilfs_segctor_collect_blocks fs/nilfs2/segment.c:1216 [inline]\n  nilfs_segctor_collect fs/nilfs2/segment.c:1540 [inline]\n  nilfs_segctor_do_construct+0x1c28/0x6b90 fs/nilfs2/segment.c:2115\n  nilfs_segctor_construct+0x181/0x6b0 fs/nilfs2/segment.c:2479\n  nilfs_segctor_thread_construct fs/nilfs2/segment.c:2587 [inline]\n  nilfs_segctor_thread+0x69e/0xe80 fs/nilfs2/segment.c:2701\n  kthread+0x2f0/0x390 kernel/kthread.c:389\n  ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147\n  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244\n  </TASK>\n\nBoth of these issues are caused by the callbacks that handle the\npage/folio write requests, forcibly clear various states, including the\nworking state of the buffers they hold, at unexpected times when they\ndetect read-only fallback.\n\nFix these issues by checking if the buffer is referenced before clearing\nthe page/folio state, and skipping the clear if it is.","Type":"Description","Title":"nilfs2: do not force clear folio if buffer is referenced"}]}}}