Description
In the Linux kernel, the following vulnerability has been resolved:
fuse: invalidate the correct range after O_APPEND direct write
fuse_direct_write_iter() captures pos before generic_write_checks(),
which moves ki_pos to EOF for O_APPEND writes:
fuse_direct_write_iter()
{
pos = iocb->ki_pos; /* 0 (user-supplied) */
generic_write_checks(); /* ki_pos -> EOF */
fuse_direct_io(); /* writes at EOF, correct */
invalidate(pos, pos + res); /* [0, res) -- wrong */
}
The post-write invalidation targets a stale range instead of the
actual written range at EOF.
This can cause data inconsistency when the file size is not
page-aligned. The tail page straddling EOF has a valid portion
before EOF that concurrent readers can fault back in during the
DIO write window:
Tail page (file size X not page-aligned):
page_start X (EOF) page_end
|--- valid data ----|-- stale --|
CPU0 (O_APPEND DIO writer) CPU1 (buffered reader)
-------------------------- ----------------------
invalidate [X, X+len)
tail page evicted
FUSE_WRITE in flight ...
read [page_start, X)
tail page re-faulted
[X, page_end) = stale
FUSE_WRITE completes
i_size = X + len
invalidate [0, len) <- WRONG
tail page still cached
read [X, X+len)
hits stale tail page
returns old data
Fix by reading pos back from iocb->ki_pos after generic_write_checks(),
as generic_file_direct_write() does.
Also fix a typo in the comment ("may have" -> "may have competed").
fuse: invalidate the correct range after O_APPEND direct write
fuse_direct_write_iter() captures pos before generic_write_checks(),
which moves ki_pos to EOF for O_APPEND writes:
fuse_direct_write_iter()
{
pos = iocb->ki_pos; /* 0 (user-supplied) */
generic_write_checks(); /* ki_pos -> EOF */
fuse_direct_io(); /* writes at EOF, correct */
invalidate(pos, pos + res); /* [0, res) -- wrong */
}
The post-write invalidation targets a stale range instead of the
actual written range at EOF.
This can cause data inconsistency when the file size is not
page-aligned. The tail page straddling EOF has a valid portion
before EOF that concurrent readers can fault back in during the
DIO write window:
Tail page (file size X not page-aligned):
page_start X (EOF) page_end
|--- valid data ----|-- stale --|
CPU0 (O_APPEND DIO writer) CPU1 (buffered reader)
-------------------------- ----------------------
invalidate [X, X+len)
tail page evicted
FUSE_WRITE in flight ...
read [page_start, X)
tail page re-faulted
[X, page_end) = stale
FUSE_WRITE completes
i_size = X + len
invalidate [0, len) <- WRONG
tail page still cached
read [X, X+len)
hits stale tail page
returns old data
Fix by reading pos back from iocb->ki_pos after generic_write_checks(),
as generic_file_direct_write() does.
Also fix a typo in the comment ("may have" -> "may have competed").
Published:
2026-09-17
Score:
n/a
EPSS:
n/a
KEV:
No
Impact:
n/a
Action:
n/a
Analysis
No analysis available yet.
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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No data.
No data available yet.
Remediation
No remediation available yet.
Tracking
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Advisories
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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: fuse: invalidate the correct range after O_APPEND direct write fuse_direct_write_iter() captures pos before generic_write_checks(), which moves ki_pos to EOF for O_APPEND writes: fuse_direct_write_iter() { pos = iocb->ki_pos; /* 0 (user-supplied) */ generic_write_checks(); /* ki_pos -> EOF */ fuse_direct_io(); /* writes at EOF, correct */ invalidate(pos, pos + res); /* [0, res) -- wrong */ } The post-write invalidation targets a stale range instead of the actual written range at EOF. This can cause data inconsistency when the file size is not page-aligned. The tail page straddling EOF has a valid portion before EOF that concurrent readers can fault back in during the DIO write window: Tail page (file size X not page-aligned): page_start X (EOF) page_end |--- valid data ----|-- stale --| CPU0 (O_APPEND DIO writer) CPU1 (buffered reader) -------------------------- ---------------------- invalidate [X, X+len) tail page evicted FUSE_WRITE in flight ... read [page_start, X) tail page re-faulted [X, page_end) = stale FUSE_WRITE completes i_size = X + len invalidate [0, len) <- WRONG tail page still cached read [X, X+len) hits stale tail page returns old data Fix by reading pos back from iocb->ki_pos after generic_write_checks(), as generic_file_direct_write() does. Also fix a typo in the comment ("may have" -> "may have competed"). | |
| Title | fuse: invalidate the correct range after O_APPEND direct write | |
| 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: 2026-09-17T16:06:08.870Z
Reserved: 2026-09-11T19:38:34.786Z
Link: CVE-2026-90096
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-17T17:17:01.233
Modified: 2026-09-17T17:17:01.233
Link: CVE-2026-90096
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.