ext4: fix e4b bitmap inconsistency reports
In the Linux kernel, the following vulnerability has been resolved: ext4: fix e4b bitmap inconsistency reports A bitmap inconsistency issue was observed during stress tests under mixed huge-page workloads. Ext4 reported multiple e4b bitmap check failures like: ext4_mb_complex_scan_group:2508: group 350, 8179 free clusters as per group info. But got 8192 blocks Analysis and experimentation confirmed that the issue is caused by a race condition between page migration and bitmap modification. Although this timing window is extremely narrow, it is still hit in practice: folio_lock ext4_mb_load_buddy __migrate_folio check ref count folio_mc_copy __filemap_get_folio folio_try_get(folio) ...... mb_mark_used ext4_mb_unload_buddy __folio_migrate_mapping folio_ref_freeze folio_unlock The root cause of this issue is that the fast path of load_buddy only increments the folio's reference count, which is insufficient to prevent concurrent folio migration. We observed that the folio migration process acquires the folio lock. Therefore, we can determine whether to take the fast path in load_buddy by checking the lock status. If the folio is locked, we opt for the slow path (which acquires the lock) to close this concurrency window. Additionally, this change addresses the following issues: When the DOUBLE_CHECK macro is enabled to inspect bitmap-related issues, the following error may be triggered: corruption in group 324 at byte 784(6272): f in copy != ff on disk/prealloc Analysis reveals th
CVE-2026-45942
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-2026-45942
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": "c9de560ded61faa5b754137b7753da252391c55a",
"lessThan": "57e83bfbe1e412ac42daced2086f3c6f9a17bba0",
"versionType": "git"
},
{
"status": "affected",
"version": "c9de560ded61faa5b754137b7753da252391c55a",
"lessThan": "c05033cfc5c7699cd4df8d48cef94d01da755f24",
"versionType": "git"
},
{
"status": "affected",
"version": "c9de560ded61faa5b754137b7753da252391c55a",
"lessThan": "29a07d691d282faf38c33d4b61839b89399110f9",
"versionType": "git"
},
{
"status": "affected",
"version": "c9de560ded61faa5b754137b7753da252391c55a",
"lessThan": "f29709a7a3fc38f5015d850504762cdef0e151f9",
"versionType": "git"
},
{
"status": "affected",
"version": "c9de560ded61faa5b754137b7753da252391c55a",
"lessThan": "bdc56a9c46b2a99c12313122b9352b619a2e719e",
"versionType": "git"
}
],
"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": "2.6.25"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "2.6.25",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.6.130",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.75",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.14",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "6.19.4",
"versionType": "semver",
"lessThanOrEqual": "6.19.*"
},
{
"status": "unaffected",
"version": "7.0",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"fs/ext4/mballoc.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-45942
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #40095 · Revision 1
- Added to Heist Feed
- Publisher date