ntfs: grow index root value before reparent header update
ntfs_ir_reparent() moves the resident index root entries into an index
block and leaves a small root stub containing the child VCN. That root
stub can be larger than the existing resident value. For example, an
empty root with value_length 48 has an index area of 32 bytes, while the
large-index root stub needs index_length and allocated_size of 40 bytes.
The current code publishes the larger index.index_length and
index.allocated_size before resizing the resident value. If the resize
returns -ENOSPC, the recovery path can call ntfs_inode_add_attrlist(),
which looks attributes up again while the root header says
allocated_size 40 but the resident value still only provides 32 bytes of
index area. Lookup-time $INDEX_ROOT validation then correctly rejects
that transient layout as corrupt.
This reproduces as a generic/013 failure under qemu. In the failing run,
the transient root had value_len=48, index_size=32, index_length=40, and
allocated_size=40, and ntfsprogs-plus ntfsck reported "Corrupt index
root in MFT record 1177".
When the root stub grows, resize the resident value before publishing the
larger root header. If the resize fails, the old root remains valid for
recovery lookups. Keep the existing header-before-resize ordering for
shrink or same-size cases so the resident value never temporarily
exposes an allocated_size beyond its bounds.
Analysis
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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 |
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| Linux | Linux | affected |
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Sat, 15 Aug 2026 06:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: ntfs: grow index root value before reparent header update ntfs_ir_reparent() moves the resident index root entries into an index block and leaves a small root stub containing the child VCN. That root stub can be larger than the existing resident value. For example, an empty root with value_length 48 has an index area of 32 bytes, while the large-index root stub needs index_length and allocated_size of 40 bytes. The current code publishes the larger index.index_length and index.allocated_size before resizing the resident value. If the resize returns -ENOSPC, the recovery path can call ntfs_inode_add_attrlist(), which looks attributes up again while the root header says allocated_size 40 but the resident value still only provides 32 bytes of index area. Lookup-time $INDEX_ROOT validation then correctly rejects that transient layout as corrupt. This reproduces as a generic/013 failure under qemu. In the failing run, the transient root had value_len=48, index_size=32, index_length=40, and allocated_size=40, and ntfsprogs-plus ntfsck reported "Corrupt index root in MFT record 1177". When the root stub grows, resize the resident value before publishing the larger root header. If the resize fails, the old root remains valid for recovery lookups. Keep the existing header-before-resize ordering for shrink or same-size cases so the resident value never temporarily exposes an allocated_size beyond its bounds. | |
| Title | ntfs: grow index root value before reparent header update | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-08-15T05:54:06.292Z
Reserved: 2026-08-09T03:40:39.912Z
Link: CVE-2026-72211
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-08-15T06:21:39.803
Modified: 2026-08-15T06:21:39.803
Link: CVE-2026-72211
Redhat
No data.
OpenCVE Enrichment
No data.
No weakness.