{"id":"CVE-2026-90131","summary":"ntfs: serialize resident iomap reads with mrec_lock","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nntfs: serialize resident iomap reads with mrec_lock\n\nntfs_read_iomap_begin_resident() walks the MFT record through\nntfs_attr_lookup() -\u003e ntfs_attr_find() without taking ni-\u003emrec_lock,\nwhile ntfs_attr_record_resize(), ntfs_make_room_for_attr() and\nntfs_resident_attr_record_add() memmove() the same base_ni-\u003emrec buffer\nunder that lock. map_mft_record() only takes a reference and does not\nserialize, so the reader can observe torn attribute length and offset\nfields while a writer is relocating the records.\n\nKCSAN reports the race between the mmap read fault path and both link()\nand unlink():\n\n  BUG: KCSAN: data-race in ntfs_attr_find / ntfs_attr_record_resize\n\n  write to 0xffff888100af1018 of 4 bytes by task 96 on cpu 1:\n   ntfs_attr_record_resize+0xd2/0x130\n   ntfs_attr_record_rm+0xad/0x530\n   ntfs_delete+0x224/0x640\n   ntfs_unlink+0x14d/0x280\n   vfs_unlink+0x157/0x520\n\n  read to 0xffff888100af1018 of 4 bytes by task 95 on cpu 0:\n   ntfs_attr_find+0x104/0x5b0\n   ntfs_attr_lookup+0x39c/0x10c0\n   ntfs_read_iomap_begin_resident+0xc6/0x230\n   ntfs_read_iomap_begin+0x5d/0xa0\n   iomap_iter+0x2e2/0x6e0\n   iomap_read_folio+0x147/0x2a0\n   ntfs_read_folio+0x108/0x170\n   filemap_read_folio+0x35/0x100\n   filemap_fault+0x993/0x1000\n\n  value changed: 0x00000250 -\u003e 0x000001f0\n\nThe address is mrec + 0x18, i.e. mft_record.bytes_in_use, and the change\nis the 96 bytes of one $FILE_NAME attribute being removed.\n\nKeep base_ni-\u003emrec_lock from the resident read iomap lookup through\niomap_end(). This protects both the attribute walk and the subsequent copy\nfrom iomap-\u003einline_data, which points into the MFT record. The non-resident\npath is left alone: ntfs_lookup() already holds the directory inode's\nmrec_lock when it reads an index folio through read_mapping_folio(), and\ntaking the lock in the shared wrapper deadlocks there with recursive locking\non mrec_lock. The comment above the read_mapping_folio() call in\nfs/ntfs/dir.c notes the same hazard.\n\nThe seek path uses the same lookup helper but does not dereference\niomap-\u003einline_data. Release the lock before returning from that path,\nwhereas the regular read path records base_ni in iomap-\u003eprivate and releases\nthe lock from its iomap_end() callback.\n\nTested with a reproducer that faults in a 16-byte resident file while\nanother thread runs link()/unlink() on it. Before: 40 KCSAN reports in\nabout one second. After: no reports in 180 seconds over 206,090 read\niterations and 423,540 link/unlink cycles. A PROVE_LOCKING build shows no\nlockdep splat with the same reproducer running for 60 seconds.","modified":"2026-09-19T03:47:28.617882442Z","published":"2026-09-17T16:06:31.913Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90131.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/0400e0d50eb3be19c98323faa322b652e4ae3f99"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d9e00c457d4ab8ab59c6e4b8554c921260e4e16c"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90131.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-90131"},{"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":"b041ca562526b3c4a71b41b80ba5e520eac636ad"},{"fixed":"0400e0d50eb3be19c98323faa322b652e4ae3f99"},{"fixed":"d9e00c457d4ab8ab59c6e4b8554c921260e4e16c"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90131.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"7.1.0"},{"fixed":"7.2.6"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90131.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:N/A:H"}]}