In the Linux kernel, the following vulnerability has been resolved:
ntfs: serialize resident iomap reads with mrec_lock
ntfs_read_iomap_begin_resident() walks the MFT record through
ntfs_attr_lookup() -> ntfs_attr_find() without taking ni->mrec_lock,
while ntfs_attr_record_resize(), ntfs_make_room_for_attr() and
ntfs_resident_attr_record_add() memmove() the same base_ni->mrec buffer
under that lock. map_mft_record() only takes a reference and does not
serialize, so the reader can observe torn attribute length and offset
fields while a writer is relocating the records.
KCSAN reports the race between the mmap read fault path and both link()
and unlink():
BUG: KCSAN: data-race in ntfs_attr_find / ntfs_attr_record_resize
write to 0xffff888100af1018 of 4 bytes by task 96 on cpu 1:
ntfs_attr_record_resize+0xd2/0x130
ntfs_attr_record_rm+0xad/0x530
ntfs_delete+0x224/0x640
ntfs_unlink+0x14d/0x280
vfs_unlink+0x157/0x520
read to 0xffff888100af1018 of 4 bytes by task 95 on cpu 0:
ntfs_attr_find+0x104/0x5b0
ntfs_attr_lookup+0x39c/0x10c0
ntfs_read_iomap_begin_resident+0xc6/0x230
ntfs_read_iomap_begin+0x5d/0xa0
iomap_iter+0x2e2/0x6e0
iomap_read_folio+0x147/0x2a0
ntfs_read_folio+0x108/0x170
filemap_read_folio+0x35/0x100
filemap_fault+0x993/0x1000
value changed: 0x00000250 -> 0x000001f0
The address is mrec + 0x18, i.e. mft_record.bytes_in_use, and the change
is the 96 bytes of one $FILE_NAME attribute being removed.
Keep base_ni->mrec_lock from the resident read iomap lookup through
iomap_end(). This protects both the attribute walk and the subsequent copy
from iomap->inline_data, which points into the MFT record. The non-resident
path is left alone: ntfs_lookup() already holds the directory inode's
mrec_lock when it reads an index folio through read_mapping_folio(), and
taking the lock in the shared wrapper deadlocks there with recursive locking
on mrec_lock. The comment above the read_mapping_folio() call in
fs/ntfs/dir.c notes the same hazard.
The seek path uses the same lookup helper but does not dereference
iomap->inline_data. Release the lock before returning from that path,
whereas the regular read path records base_ni in iomap->private and releases
the lock from its iomap_end() callback.
Tested with a reproducer that faults in a 16-byte resident file while
another thread runs link()/unlink() on it. Before: 40 KCSAN reports in
about one second. After: no reports in 180 seconds over 206,090 read
iterations and 423,540 link/unlink cycles. A PROVE_LOCKING build shows no
lockdep splat with the same reproducer running for 60 seconds.
ntfs: serialize resident iomap reads with mrec_lock
ntfs_read_iomap_begin_resident() walks the MFT record through
ntfs_attr_lookup() -> ntfs_attr_find() without taking ni->mrec_lock,
while ntfs_attr_record_resize(), ntfs_make_room_for_attr() and
ntfs_resident_attr_record_add() memmove() the same base_ni->mrec buffer
under that lock. map_mft_record() only takes a reference and does not
serialize, so the reader can observe torn attribute length and offset
fields while a writer is relocating the records.
KCSAN reports the race between the mmap read fault path and both link()
and unlink():
BUG: KCSAN: data-race in ntfs_attr_find / ntfs_attr_record_resize
write to 0xffff888100af1018 of 4 bytes by task 96 on cpu 1:
ntfs_attr_record_resize+0xd2/0x130
ntfs_attr_record_rm+0xad/0x530
ntfs_delete+0x224/0x640
ntfs_unlink+0x14d/0x280
vfs_unlink+0x157/0x520
read to 0xffff888100af1018 of 4 bytes by task 95 on cpu 0:
ntfs_attr_find+0x104/0x5b0
ntfs_attr_lookup+0x39c/0x10c0
ntfs_read_iomap_begin_resident+0xc6/0x230
ntfs_read_iomap_begin+0x5d/0xa0
iomap_iter+0x2e2/0x6e0
iomap_read_folio+0x147/0x2a0
ntfs_read_folio+0x108/0x170
filemap_read_folio+0x35/0x100
filemap_fault+0x993/0x1000
value changed: 0x00000250 -> 0x000001f0
The address is mrec + 0x18, i.e. mft_record.bytes_in_use, and the change
is the 96 bytes of one $FILE_NAME attribute being removed.
Keep base_ni->mrec_lock from the resident read iomap lookup through
iomap_end(). This protects both the attribute walk and the subsequent copy
from iomap->inline_data, which points into the MFT record. The non-resident
path is left alone: ntfs_lookup() already holds the directory inode's
mrec_lock when it reads an index folio through read_mapping_folio(), and
taking the lock in the shared wrapper deadlocks there with recursive locking
on mrec_lock. The comment above the read_mapping_folio() call in
fs/ntfs/dir.c notes the same hazard.
The seek path uses the same lookup helper but does not dereference
iomap->inline_data. Release the lock before returning from that path,
whereas the regular read path records base_ni in iomap->private and releases
the lock from its iomap_end() callback.
Tested with a reproducer that faults in a 16-byte resident file while
another thread runs link()/unlink() on it. Before: 40 KCSAN reports in
about one second. After: no reports in 180 seconds over 206,090 read
iterations and 423,540 link/unlink cycles. A PROVE_LOCKING build shows no
lockdep splat with the same reproducer running for 60 seconds.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
|
|||||||||||||||
| Linux | Linux | affected |
|
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Advisories
No advisories yet.
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Thu, 17 Sep 2026 16:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: ntfs: serialize resident iomap reads with mrec_lock ntfs_read_iomap_begin_resident() walks the MFT record through ntfs_attr_lookup() -> ntfs_attr_find() without taking ni->mrec_lock, while ntfs_attr_record_resize(), ntfs_make_room_for_attr() and ntfs_resident_attr_record_add() memmove() the same base_ni->mrec buffer under that lock. map_mft_record() only takes a reference and does not serialize, so the reader can observe torn attribute length and offset fields while a writer is relocating the records. KCSAN reports the race between the mmap read fault path and both link() and unlink(): BUG: KCSAN: data-race in ntfs_attr_find / ntfs_attr_record_resize write to 0xffff888100af1018 of 4 bytes by task 96 on cpu 1: ntfs_attr_record_resize+0xd2/0x130 ntfs_attr_record_rm+0xad/0x530 ntfs_delete+0x224/0x640 ntfs_unlink+0x14d/0x280 vfs_unlink+0x157/0x520 read to 0xffff888100af1018 of 4 bytes by task 95 on cpu 0: ntfs_attr_find+0x104/0x5b0 ntfs_attr_lookup+0x39c/0x10c0 ntfs_read_iomap_begin_resident+0xc6/0x230 ntfs_read_iomap_begin+0x5d/0xa0 iomap_iter+0x2e2/0x6e0 iomap_read_folio+0x147/0x2a0 ntfs_read_folio+0x108/0x170 filemap_read_folio+0x35/0x100 filemap_fault+0x993/0x1000 value changed: 0x00000250 -> 0x000001f0 The address is mrec + 0x18, i.e. mft_record.bytes_in_use, and the change is the 96 bytes of one $FILE_NAME attribute being removed. Keep base_ni->mrec_lock from the resident read iomap lookup through iomap_end(). This protects both the attribute walk and the subsequent copy from iomap->inline_data, which points into the MFT record. The non-resident path is left alone: ntfs_lookup() already holds the directory inode's mrec_lock when it reads an index folio through read_mapping_folio(), and taking the lock in the shared wrapper deadlocks there with recursive locking on mrec_lock. The comment above the read_mapping_folio() call in fs/ntfs/dir.c notes the same hazard. The seek path uses the same lookup helper but does not dereference iomap->inline_data. Release the lock before returning from that path, whereas the regular read path records base_ni in iomap->private and releases the lock from its iomap_end() callback. Tested with a reproducer that faults in a 16-byte resident file while another thread runs link()/unlink() on it. Before: 40 KCSAN reports in about one second. After: no reports in 180 seconds over 206,090 read iterations and 423,540 link/unlink cycles. A PROVE_LOCKING build shows no lockdep splat with the same reproducer running for 60 seconds. | |
| Title | ntfs: serialize resident iomap reads with mrec_lock | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-09-17T16:06:31.913Z
Reserved: 2026-09-11T19:38:34.788Z
Link: CVE-2026-90131
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-17T17:17:05.617
Modified: 2026-09-17T17:17:05.617
Link: CVE-2026-90131
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.