ext4: handle wraparound when searching for blocks for indirect mapped blocks
In the Linux kernel, the following vulnerability has been resolved: ext4: handle wraparound when searching for blocks for indirect mapped blocks Commit 4865c768b563 ("ext4: always allocate blocks only from groups inode can use") restricts what blocks will be allocated for indirect block based files to block numbers that fit within 32-bit block numbers. However, when using a review bot running on the latest Gemini LLM to check this commit when backporting into an LTS based kernel, it raised this concern: If ac->ac_g_ex.fe_group is >= ngroups (for instance, if the goal group was populated via stream allocation from s_mb_last_groups), then start will be >= ngroups. Does this allow allocating blocks beyond the 32-bit limit for indirect block mapped files? The commit message mentions that ext4_mb_scan_groups_linear() takes care to not select unsupported groups. However, its loop uses group = *start, and the very first iteration will call ext4_mb_scan_group() with this unsupported group because next_linear_group() is only called at the end of the iteration. After reviewing the code paths involved and considering the LLM review, I determined that this can happen when there is a file system where some files/directories are extent-mapped and others are indirect-block mapped. To address this, add a safety clamp in ext4_mb_scan_groups().
CVE-2026-43067
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-2026-43067
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": "9d89b9d55e25cb340c5b4b769876edc551b7a9ff",
"lessThan": "f89bba144938921a2249237ad04a0183ff3f8930",
"versionType": "git"
},
{
"status": "affected",
"version": "1b0edd6022a3f44ce87fea9959a9310f4628fbea",
"lessThan": "83170a05908b6cf2fb3235d3065bf613ff866f3c",
"versionType": "git"
},
{
"status": "affected",
"version": "9eea2f57d11b30049ff996ac3eff6e0dc8089e5f",
"lessThan": "4bec4a498ce86314d470ae6144120461f2138c29",
"versionType": "git"
},
{
"status": "affected",
"version": "34c803edc0b3365a42efcf9815acab63b4cf54e0",
"lessThan": "12624c5b724a81e14e532972b40d863b0de3b7d1",
"versionType": "git"
},
{
"status": "affected",
"version": "321ed8d559c951e71ad2d2d69a4cf0445644e865",
"lessThan": "2a368ccddfc492a0aa951e2caef2985f20e96503",
"versionType": "git"
},
{
"status": "affected",
"version": "4865c768b563deff1b6a6384e74a62f143427b42",
"lessThan": "bb81702370fad22c06ca12b6e1648754dbc37e0f",
"versionType": "git"
},
{
"status": "affected",
"version": "16fce6b6c0b247258c6c217fce5a48abf50f6964",
"versionType": "git"
},
{
"status": "affected",
"version": "5.15.203",
"lessThan": "5.16",
"versionType": "semver"
}
],
"programFiles": [
"fs/ext4/mballoc.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.1.167",
"lessThan": "6.1.168",
"versionType": "semver"
},
{
"status": "affected",
"version": "6.6.130",
"lessThan": "6.6.134",
"versionType": "semver"
},
{
"status": "affected",
"version": "6.12.77",
"lessThan": "6.12.80",
"versionType": "semver"
},
{
"status": "affected",
"version": "6.18.14",
"lessThan": "6.18.21",
"versionType": "semver"
},
{
"status": "affected",
"version": "6.19.4",
"lessThan": "6.19.11",
"versionType": "semver"
}
],
"programFiles": [
"fs/ext4/mballoc.c"
],
"defaultStatus": "unaffected"
}
]- Related CVEs
- CVE-2026-43067
Source reference:
/cveMetadata/cveId
Publisher severity
critical
Source reference: /containers/cna/metrics
- Event
- #40017 · Revision 1
- Added to Heist Feed
- Publisher date