smb/client: handle overlapping allocated ranges in fallocate
In the Linux kernel, the following vulnerability has been resolved: smb/client: handle overlapping allocated ranges in fallocate smb3_simple_fallocate_range() can skip holes when an allocated range returned by the server starts before the current fallocate offset. The skipped hole is not zero-filled, but fallocate still returns success. A later write to that hole may therefore fail with ENOSPC. The function queries allocated ranges so that it can preserve existing contents and write zeroes only into holes. However, the server may return a range that starts before the current fallocate offset. For example, assume the fallocate request is [100, 400) and the only allocated range returned by the server is [0, 200): Request: [100, 400) Server range: [ 0, 200) allocated Correct: [100, 200) allocated data, skip [200, 400) hole, zero-fill Current: [100, 300) skipped [300, 400) zero-filled afterwards The current code adds the full server range length, 200, to the current offset 100 and moves to 300. As a result, the hole in [200, 300) is skipped without being zero-filled. Fix this by advancing only over the part of the allocated range that overlaps the current fallocate offset. Ignore ranges that end before the current offset and reject ranges whose end offset overflows. This also prevents a malformed range length from causing an out-of-bounds zero-buffer read.
CVE-2026-68388
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-2026-68388
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": "c406bb9ece6ef63721daab106f132ff4b4234e81",
"lessThan": "aeb58a4eb39a7ff4d7782b4f4ada0fda5e0675d2",
"versionType": "git"
},
{
"status": "affected",
"version": "966a3cb7c7db786452a87afdc3b48858fc4d4d6b",
"lessThan": "01719883235507b1585e4c51e320d9a7113dc698",
"versionType": "git"
},
{
"status": "affected",
"version": "966a3cb7c7db786452a87afdc3b48858fc4d4d6b",
"lessThan": "f47c7277c03a636fcc3a57969f2dc09567b3c050",
"versionType": "git"
},
{
"status": "affected",
"version": "966a3cb7c7db786452a87afdc3b48858fc4d4d6b",
"lessThan": "437637f5ff3f573b2edf8571de91fb00a21eb4e6",
"versionType": "git"
},
{
"status": "affected",
"version": "966a3cb7c7db786452a87afdc3b48858fc4d4d6b",
"lessThan": "377fe3e583e46369ee1004d5cfe12271d6589a68",
"versionType": "git"
},
{
"status": "affected",
"version": "966a3cb7c7db786452a87afdc3b48858fc4d4d6b",
"lessThan": "7e08ab7a061b17ac1989a225c6afb53f44a86808",
"versionType": "git"
},
{
"status": "affected",
"version": "966a3cb7c7db786452a87afdc3b48858fc4d4d6b",
"lessThan": "a4a09e5142835633fffbde68bd0a039ba4d4bf97",
"versionType": "git"
},
{
"status": "affected",
"version": "966a3cb7c7db786452a87afdc3b48858fc4d4d6b",
"lessThan": "b09ae45d85dc816987a71db9eebc54b0ae288e94",
"versionType": "git"
},
{
"status": "affected",
"version": "2f9f4a2d0e6fcf0673ed51195e06e47abe966900",
"versionType": "git"
},
{
"status": "affected",
"version": "5e397c943424de94879830e72c95f2679e297a76",
"versionType": "git"
},
{
"status": "affected",
"version": "5.10.50",
"lessThan": "5.10.265",
"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": "5.10.265",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.216",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.183",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.148",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.101",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.42",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.1.6",
"versionType": "semver",
"lessThanOrEqual": "7.1.*"
},
{
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"fs/smb/client/smb2ops.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-68388
Source reference:
/cveMetadata/cveId
Publisher severity
critical
Source reference: /containers/cna/metrics
- Event
- #41713 · Revision 1
- Added to Heist Feed
- Publisher date