mm/khugepaged: invoke MMU notifiers in shmem/file collapse paths
In the Linux kernel, the following vulnerability has been resolved: mm/khugepaged: invoke MMU notifiers in shmem/file collapse paths Any codepath that zaps page table entries must invoke MMU notifiers to ensure that secondary MMUs (like KVM) don't keep accessing pages which aren't mapped anymore. Secondary MMUs don't hold their own references to pages that are mirrored over, so failing to notify them can lead to page use-after-free. I'm marking this as addressing an issue introduced in commit f3f0e1d2150b ("khugepaged: add support of collapse for tmpfs/shmem pages"), but most of the security impact of this only came in commit 27e1f8273113 ("khugepaged: enable collapse pmd for pte-mapped THP"), which actually omitted flushes for the removal of present PTEs, not just for the removal of empty page tables.
- Products
- Kernel
- Affected versions
- Not specified
- Fixed versions
- 4.14.303, 4.19.270, 4.9.337, 5.10.159, 5.15.83, 5.4.227, 6.0.13
- CVEs
- CVE-2022-48991
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 4 Nov 2026, 20:52 UTC · Revision 1
Source evidence
mm/khugepaged: invoke MMU notifiers in shmem/file collapse paths
core-osv · Original sourcePublished 21 Oct 2024, 20:06 UTC
In the Linux kernel, the following vulnerability has been resolved: mm/khugepaged: invoke MMU notifiers in shmem/file collapse paths Any codepath that zaps page table entries must invoke MMU notifiers to ensure that secondary MMUs (like KVM) don't keep accessing pages which aren't mapped anymore. Secondary MMUs don't hold their own references to pages that are mirrored over, so failing to notify them can lead to page use-after-free. I'm marking this as addressing an issue introduced in commit f3f0e1d2150b ("khugepaged: add support of collapse for tmpfs/shmem pages"), but most of the security impact of this only came in commit 27e1f8273113 ("khugepaged: enable collapse pmd for pte-mapped THP"), which actually omitted flushes for the removal of present PTEs, not just for the removal of empty page tables.
osv:CVE-2022-48991
Kernel
Fixed versions: 4.9.337, 4.14.303, 4.19.270, 5.4.227, 5.10.159, 5.15.83, 6.0.13
Complete source record
{
"id": "9fabca41a043fefb3373d2cfff0d9e1692bd54b47e6fb3e90aa155f7c31e895b",
"url": "https://osv.dev/vulnerability/CVE-2022-48991",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "mm/khugepaged: invoke MMU notifiers in shmem/file collapse paths",
"summary": "In the Linux kernel, the following vulnerability has been resolved: mm/khugepaged: invoke MMU notifiers in shmem/file collapse paths Any codepath that zaps page table entries must invoke MMU notifiers to ensure that secondary MMUs (like KVM) don't keep accessing pages which aren't mapped anymore. Secondary MMUs don't hold their own references to pages that are mirrored over, so failing to notify them can lead to page use-after-free. I'm marking this as addressing an issue introduced in commit f3f0e1d2150b (\"khugepaged: add support of collapse for tmpfs/shmem pages\"), but most of the security impact of this only came in commit 27e1f8273113 (\"khugepaged: enable collapse pmd for pte-mapped THP\"), which actually omitted flushes for the removal of present PTEs, not just for the removal of empty page tables.",
"evidence": "osv:CVE-2022-48991",
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"severity": "high",
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"aliases": [
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"metrics": [
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"type": "CVSS_V3",
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H"
}
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"affected": [
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"modified": "2026-10-28T02:30:39.843683563Z",
"provider": "osv",
"references": [
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"https://git.kernel.org/stable/c/275c626c131cfe141beeb6c575e31fa53d32da19",
"https://git.kernel.org/stable/c/5450535901d89a5dcca5fbbc59a24fe89caeb465",
"https://git.kernel.org/stable/c/5ffc2a75534d9d74d49760f983f8eb675fa63d69",
"https://git.kernel.org/stable/c/7f445ca2e0e59c7971d0b7b853465e50844ab596",
"https://git.kernel.org/stable/c/c23105673228c349739e958fa33955ed8faddcaf",
"https://git.kernel.org/stable/c/f268f6cf875f3220afc77bdd0bf1bb136eb54db9",
"https://git.kernel.org/stable/c/ff2a1a6f869650aec99e9d070b5ab625bfbc5bc3",
"https://github.com/CVEProject/cvelistV5/tree/main/cves/2022/48xxx/CVE-2022-48991.json",
"https://nvd.nist.gov/vuln/detail/CVE-2022-48991",
"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
],
"provider_metadata": {
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"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2022/48xxx/CVE-2022-48991.json"
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},
"related_cves": [
{
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"evidence": "/id"
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"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 506897,
"published_at": "2024-10-21T20:06:08.312+00:00"
}