CVE-2026-43389 (GCVE-0-2026-43389)
Vulnerability from cvelistv5 – Published: 2026-05-08 14:21 – Updated: 2026-05-08 14:21
VLAI?
Title
mm: memfd_luo: always dirty all folios
Summary
In the Linux kernel, the following vulnerability has been resolved:
mm: memfd_luo: always dirty all folios
A dirty folio is one which has been written to. A clean folio is its
opposite. Since a clean folio has no user data, it can be freed under
memory pressure.
memfd preservation with LUO saves the flag at preserve(). This is
problematic. The folio might get dirtied later. Saving it at freeze()
also doesn't work, since the dirty bit from PTE is normally synced at
unmap and there might still be mappings of the file at freeze().
To see why this is a problem, say a folio is clean at preserve, but gets
dirtied later. The serialized state of the folio will mark it as clean.
After retrieve, the next kernel will see the folio as clean and might try
to reclaim it under memory pressure. This will result in losing user
data.
Mark all folios of the file as dirty, and always set the
MEMFD_LUO_FOLIO_DIRTY flag. This comes with the side effect of making all
clean folios un-reclaimable. This is a cost that has to be paid for
participants of live update. It is not expected to be a common use case
to preserve a lot of clean folios anyway.
Since the value of pfolio->flags is a constant now, drop the flags
variable and set it directly.
Severity ?
No CVSS data available.
Assigner
References
Impacted products
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"containers": {
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{
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"product": "Linux",
"programFiles": [
"mm/memfd_luo.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
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{
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"programFiles": [
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"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.19"
},
{
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"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "6.19.9",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.0",
"versionType": "original_commit_for_fix"
}
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],
"cpeApplicability": [
{
"nodes": [
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"cpeMatch": [
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"versionStartIncluding": "6.19",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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}
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"negate": false,
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm: memfd_luo: always dirty all folios\n\nA dirty folio is one which has been written to. A clean folio is its\nopposite. Since a clean folio has no user data, it can be freed under\nmemory pressure.\n\nmemfd preservation with LUO saves the flag at preserve(). This is\nproblematic. The folio might get dirtied later. Saving it at freeze()\nalso doesn\u0027t work, since the dirty bit from PTE is normally synced at\nunmap and there might still be mappings of the file at freeze().\n\nTo see why this is a problem, say a folio is clean at preserve, but gets\ndirtied later. The serialized state of the folio will mark it as clean. \nAfter retrieve, the next kernel will see the folio as clean and might try\nto reclaim it under memory pressure. This will result in losing user\ndata.\n\nMark all folios of the file as dirty, and always set the\nMEMFD_LUO_FOLIO_DIRTY flag. This comes with the side effect of making all\nclean folios un-reclaimable. This is a cost that has to be paid for\nparticipants of live update. It is not expected to be a common use case\nto preserve a lot of clean folios anyway.\n\nSince the value of pfolio-\u003eflags is a constant now, drop the flags\nvariable and set it directly."
}
],
"providerMetadata": {
"dateUpdated": "2026-05-08T14:21:34.658Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
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"url": "https://git.kernel.org/stable/c/e901c871d4b592f0042e30f3a0f031eae79744ec"
},
{
"url": "https://git.kernel.org/stable/c/7e04bf1f33151a30e06a65b74b5f2c19fc2be128"
}
],
"title": "mm: memfd_luo: always dirty all folios",
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"cveId": "CVE-2026-43389",
"datePublished": "2026-05-08T14:21:34.658Z",
"dateReserved": "2026-05-01T14:12:56.007Z",
"dateUpdated": "2026-05-08T14:21:34.658Z",
"state": "PUBLISHED"
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"vulnerability-lookup:meta": {
"nvd": "{\"cve\":{\"id\":\"CVE-2026-43389\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-05-08T15:16:50.290\",\"lastModified\":\"2026-05-08T15:16:50.290\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nmm: memfd_luo: always dirty all folios\\n\\nA dirty folio is one which has been written to. A clean folio is its\\nopposite. Since a clean folio has no user data, it can be freed under\\nmemory pressure.\\n\\nmemfd preservation with LUO saves the flag at preserve(). This is\\nproblematic. The folio might get dirtied later. Saving it at freeze()\\nalso doesn\u0027t work, since the dirty bit from PTE is normally synced at\\nunmap and there might still be mappings of the file at freeze().\\n\\nTo see why this is a problem, say a folio is clean at preserve, but gets\\ndirtied later. The serialized state of the folio will mark it as clean. \\nAfter retrieve, the next kernel will see the folio as clean and might try\\nto reclaim it under memory pressure. This will result in losing user\\ndata.\\n\\nMark all folios of the file as dirty, and always set the\\nMEMFD_LUO_FOLIO_DIRTY flag. This comes with the side effect of making all\\nclean folios un-reclaimable. This is a cost that has to be paid for\\nparticipants of live update. It is not expected to be a common use case\\nto preserve a lot of clean folios anyway.\\n\\nSince the value of pfolio-\u003eflags is a constant now, drop the flags\\nvariable and set it directly.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/7e04bf1f33151a30e06a65b74b5f2c19fc2be128\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/e901c871d4b592f0042e30f3a0f031eae79744ec\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
}
}
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Sightings
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Nomenclature
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