{"id":"DEBIAN-CVE-2025-21722","details":"In the Linux kernel, the following vulnerability has been resolved:  nilfs2: do not force clear folio if buffer is referenced  Patch series \"nilfs2: protect busy buffer heads from being force-cleared\".  This series fixes the buffer head state inconsistency issues reported by syzbot that occurs when the filesystem is corrupted and falls back to read-only, and the associated buffer head use-after-free issue.   This patch (of 2):  Syzbot has reported that after nilfs2 detects filesystem corruption and falls back to read-only, inconsistencies in the buffer state may occur.  One of the inconsistencies is that when nilfs2 calls mark_buffer_dirty() to set a data or metadata buffer as dirty, but it detects that the buffer is not in the uptodate state:   WARNING: CPU: 0 PID: 6049 at fs/buffer.c:1177 mark_buffer_dirty+0x2e5/0x520   fs/buffer.c:1177  ...  Call Trace:   \u003cTASK\u003e   nilfs_palloc_commit_alloc_entry+0x4b/0x160 fs/nilfs2/alloc.c:598   nilfs_ifile_create_inode+0x1dd/0x3a0 fs/nilfs2/ifile.c:73   nilfs_new_inode+0x254/0x830 fs/nilfs2/inode.c:344   nilfs_mkdir+0x10d/0x340 fs/nilfs2/namei.c:218   vfs_mkdir+0x2f9/0x4f0 fs/namei.c:4257   do_mkdirat+0x264/0x3a0 fs/namei.c:4280   __do_sys_mkdirat fs/namei.c:4295 [inline]   __se_sys_mkdirat fs/namei.c:4293 [inline]   __x64_sys_mkdirat+0x87/0xa0 fs/namei.c:4293   do_syscall_x64 arch/x86/entry/common.c:52 [inline]   do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83   entry_SYSCALL_64_after_hwframe+0x77/0x7f  The other is when nilfs_btree_propagate(), which propagates the dirty state to the ancestor nodes of a b-tree that point to a dirty buffer, detects that the origin buffer is not dirty, even though it should be:   WARNING: CPU: 0 PID: 5245 at fs/nilfs2/btree.c:2089   nilfs_btree_propagate+0xc79/0xdf0 fs/nilfs2/btree.c:2089  ...  Call Trace:   \u003cTASK\u003e   nilfs_bmap_propagate+0x75/0x120 fs/nilfs2/bmap.c:345   nilfs_collect_file_data+0x4d/0xd0 fs/nilfs2/segment.c:587   nilfs_segctor_apply_buffers+0x184/0x340 fs/nilfs2/segment.c:1006   nilfs_segctor_scan_file+0x28c/0xa50 fs/nilfs2/segment.c:1045   nilfs_segctor_collect_blocks fs/nilfs2/segment.c:1216 [inline]   nilfs_segctor_collect fs/nilfs2/segment.c:1540 [inline]   nilfs_segctor_do_construct+0x1c28/0x6b90 fs/nilfs2/segment.c:2115   nilfs_segctor_construct+0x181/0x6b0 fs/nilfs2/segment.c:2479   nilfs_segctor_thread_construct fs/nilfs2/segment.c:2587 [inline]   nilfs_segctor_thread+0x69e/0xe80 fs/nilfs2/segment.c:2701   kthread+0x2f0/0x390 kernel/kthread.c:389   ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147   ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244   \u003c/TASK\u003e  Both of these issues are caused by the callbacks that handle the page/folio write requests, forcibly clear various states, including the working state of the buffers they hold, at unexpected times when they detect read-only fallback.  Fix these issues by checking if the buffer is referenced before clearing the page/folio state, and skipping the clear if it is.","modified":"2026-09-01T16:06:09.779534259Z","published":"2025-02-27T02:15:15.883Z","upstream":["CVE-2025-21722"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2025-21722"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.129-1"}]}],"versions":["6.1.106-1","6.1.106-2","6.1.106-3","6.1.112-1","6.1.115-1","6.1.119-1","6.1.123-1","6.1.124-1","6.1.128-1","6.1.27-1","6.1.37-1","6.1.38-1","6.1.38-2","6.1.38-2~bpo11+1","6.1.38-3","6.1.38-4","6.1.38-4~bpo11+1","6.1.52-1","6.1.55-1","6.1.55-1~bpo11+1","6.1.64-1","6.1.66-1","6.1.67-1","6.1.69-1","6.1.69-1~bpo11+1","6.1.76-1","6.1.76-1~bpo11+1","6.1.82-1","6.1.85-1","6.1.90-1","6.1.90-1~bpo11+1","6.1.94-1","6.1.94-1~bpo11+1","6.1.98-1","6.1.99-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2025-21722.json"}},{"package":{"name":"linux","ecosystem":"Debian:13","purl":"pkg:deb/debian/linux?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.12.13-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2025-21722.json"}},{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.12.13-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2025-21722.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}