{"id":"CVE-2025-21722","summary":"nilfs2: do not force clear folio if buffer is referenced","details":"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  \u003cTASK\u003e\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  \u003cTASK\u003e\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  \u003c/TASK\u003e\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.","modified":"2026-03-20T12:41:08.116053Z","published":"2025-02-27T02:07:30.387Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/21xxx/CVE-2025-21722.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/1098bb8d52419d262a3358d099a1598a920b730f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/19296737024cd220a1d6590bf4c092bca8c99497"},{"type":"WEB","url":"https://git.kernel.org/stable/c/4d042811c72f71be7c14726db2c72b67025a7cb5"},{"type":"WEB","url":"https://git.kernel.org/stable/c/557ccf5e49f1fb848a29698585bcab2e50a597ef"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7d0544bacc11d6aa26ecd7debf9353193c7a3328"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ca76bb226bf47ff04c782cacbd299f12ddee1ec1"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f51ff43c4c5a6c8e72d0aca89e4d5e688938412f"},{"type":"WEB","url":"https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html"},{"type":"WEB","url":"https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/21xxx/CVE-2025-21722.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-21722"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"8c26c4e2694a163d525976e804d81cd955bbb40c"},{"fixed":"7d0544bacc11d6aa26ecd7debf9353193c7a3328"},{"fixed":"4d042811c72f71be7c14726db2c72b67025a7cb5"},{"fixed":"f51ff43c4c5a6c8e72d0aca89e4d5e688938412f"},{"fixed":"19296737024cd220a1d6590bf4c092bca8c99497"},{"fixed":"1098bb8d52419d262a3358d099a1598a920b730f"},{"fixed":"557ccf5e49f1fb848a29698585bcab2e50a597ef"},{"fixed":"ca76bb226bf47ff04c782cacbd299f12ddee1ec1"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2025-21722.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}