xfs: fix exchange-range reflink flag clearing issue with INO1_WRITTEN
When exchanging two full-file ranges, xmi_can_exchange_reflink_flags()
can move the reflink inode flag from the file that currently has it to
the other file, as long as exactly one side is marked. This assumes
that the file contents, and therefore all shared extents, are exchanged.
That assumption is not true when XFS_EXCHMAPS_INO1_WRITTEN is set.
xfs_exchmaps_can_skip_mapping() can skip hole and unwritten mappings
from file1, so an exchange can complete without moving every mapping
that the earlier flag-swap decision accounted for. In that case the
post-operation cleanup can clear the reflink flag from an inode that
still owns shared written extents. Later writes then take the
non-reflink write path and may update blocks that should still have
been protected by CoW, which shows up as data corruption between
reflink-related files.
Fix this by disabling the reflink flag exchange whenever
XFS_EXCHMAPS_INO1_WRITTEN is requested. The contents exchange can still
proceed; the conservative outcome is that both inodes keep the reflink
flag. The regular reflink flag cleanup path can drop the extra flag
later once the inode no longer has shared extents.
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Linux
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Solution
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Workaround
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Wed, 26 Aug 2026 17:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-665 |
Wed, 26 Aug 2026 14:45:00 +0000
| Type | Values Removed | Values Added |
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| Description | In the Linux kernel, the following vulnerability has been resolved: xfs: fix exchange-range reflink flag clearing issue with INO1_WRITTEN When exchanging two full-file ranges, xmi_can_exchange_reflink_flags() can move the reflink inode flag from the file that currently has it to the other file, as long as exactly one side is marked. This assumes that the file contents, and therefore all shared extents, are exchanged. That assumption is not true when XFS_EXCHMAPS_INO1_WRITTEN is set. xfs_exchmaps_can_skip_mapping() can skip hole and unwritten mappings from file1, so an exchange can complete without moving every mapping that the earlier flag-swap decision accounted for. In that case the post-operation cleanup can clear the reflink flag from an inode that still owns shared written extents. Later writes then take the non-reflink write path and may update blocks that should still have been protected by CoW, which shows up as data corruption between reflink-related files. Fix this by disabling the reflink flag exchange whenever XFS_EXCHMAPS_INO1_WRITTEN is requested. The contents exchange can still proceed; the conservative outcome is that both inodes keep the reflink flag. The regular reflink flag cleanup path can drop the extra flag later once the inode no longer has shared extents. | |
| Title | xfs: fix exchange-range reflink flag clearing issue with INO1_WRITTEN | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-08-26T14:37:07.990Z
Reserved: 2026-08-26T14:34:25.764Z
Link: CVE-2026-80530
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-08-26T15:17:06.990
Modified: 2026-08-26T15:17:06.990
Link: CVE-2026-80530
Redhat
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OpenCVE Enrichment
Updated: 2026-08-26T18:15:08Z