smb: client: flush and commit data before querying allocated ranges
In the Linux kernel, the following vulnerability has been resolved: smb: client: flush and commit data before querying allocated ranges The mode 0 / FALLOC_FL_KEEP_SIZE fallocate emulation for small interior ranges in smb3_simple_fallocate_range() issues FSCTL_QUERY_ALLOCATED_RANGES and zero-fills any sub-range the server reports as an unallocated hole, to force block allocation without changing file contents. This is unsafe against Windows servers. Per the Win32 documentation, FSCTL_QUERY_ALLOCATED_RANGES only reports ranges that *may* contain nonzero data and is explicitly not coherent with recently written data: "a call to FSCTL_QUERY_ALLOCATED_RANGES [after writing to a network file] would not necessarily return a correct list of allocated regions. To ensure coherency [...] flush the data to the file" fsx (generic/363) reproduces the resulting corruption against Windows Server 2022: a range is written, an uncached read returns the data, yet the next FSCTL_QUERY_ALLOCATED_RANGES on that range reports it as a whole hole, so the emulation overwrites live data with zeroes. A network trace confirmed the WRITE, the READ returning data and the query returning an empty range list within microseconds. Samba does not exhibit this; its query is coherent with the written data. Write back the dirty pages, drain any outstanding I/O and issue an SMB2 FLUSH to force the server to commit the data before querying the allocated ranges, so the query reflects the data actually present. With t
CVE-2026-98684
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-98684
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "966a3cb7c7db786452a87afdc3b48858fc4d4d6b",
"lessThan": "f82242fe3109a3ef72f429540b5bdde08fbfb0e4",
"versionType": "git"
},
{
"status": "affected",
"version": "966a3cb7c7db786452a87afdc3b48858fc4d4d6b",
"lessThan": "bf84e44ff0ed802778eafd7ecb623635379cb506",
"versionType": "git"
},
{
"status": "affected",
"version": "966a3cb7c7db786452a87afdc3b48858fc4d4d6b",
"lessThan": "aa994489bd835547c191827acc460192e147032d",
"versionType": "git"
},
{
"status": "affected",
"version": "c406bb9ece6ef63721daab106f132ff4b4234e81",
"versionType": "git"
},
{
"status": "affected",
"version": "2f9f4a2d0e6fcf0673ed51195e06e47abe966900",
"versionType": "git"
},
{
"status": "affected",
"version": "5e397c943424de94879830e72c95f2679e297a76",
"versionType": "git"
},
{
"status": "affected",
"version": "5.10.50",
"lessThan": "5.11",
"versionType": "semver"
},
{
"status": "affected",
"version": "5.12.17",
"lessThan": "5.13",
"versionType": "semver"
},
{
"status": "affected",
"version": "5.13.2",
"lessThan": "5.14",
"versionType": "semver"
}
],
"programFiles": [
"fs/smb/client/smb2ops.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "5.14"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "5.14",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.18.56",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.10",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"fs/smb/client/smb2ops.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-98684
Source reference:
/cveMetadata/cveId
Publisher severity
No explicit severity was provided.
- Event
- #38686 · Revision 1
- Added to Heist Feed
- Publisher date