mm/hugetlb: fix hugetlb_pmd_shared()
In the Linux kernel, the following vulnerability has been resolved: mm/hugetlb: fix hugetlb_pmd_shared() Patch series "mm/hugetlb: fixes for PMD table sharing (incl. using mmu_gather)", v3. One functional fix, one performance regression fix, and two related comment fixes. I cleaned up my prototype I recently shared [1] for the performance fix, deferring most of the cleanups I had in the prototype to a later point. While doing that I identified the other things. The goal of this patch set is to be backported to stable trees "fairly" easily. At least patch #1 and #4. Patch #1 fixes hugetlb_pmd_shared() not detecting any sharing Patch #2 + #3 are simple comment fixes that patch #4 interacts with. Patch #4 is a fix for the reported performance regression due to excessive IPI broadcasts during fork()+exit(). The last patch is all about TLB flushes, IPIs and mmu_gather. Read: complicated There are plenty of cleanups in the future to be had + one reasonable optimization on x86. But that's all out of scope for this series. Runtime tested, with a focus on fixing the performance regression using the original reproducer [2] on x86. This patch (of 4): We switched from (wrongly) using the page count to an independent shared count. Now, shared page tables have a refcount of 1 (excluding speculative references) and instead use ptdesc->pt_share_count to identify sharing. We didn't convert hugetlb_pmd_shared(), so right now, we would never detect a shared PMD table as such, because sharing/un
CVE-2026-23100
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-2026-23100
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",
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"version": "94b4b41d0cdf5cfd4d4325bc0e6e9e0d0e996133",
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"versionType": "git"
},
{
"status": "affected",
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{
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{
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{
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{
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{
"status": "affected",
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{
"status": "affected",
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"lessThan": "5.15.203",
"versionType": "semver"
},
{
"status": "affected",
"version": "6.1.142",
"lessThan": "6.1.167",
"versionType": "semver"
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{
"status": "affected",
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},
{
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],
"programFiles": [
"include/linux/hugetlb.h"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
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{
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{
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{
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{
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"lessThanOrEqual": "6.1.*"
},
{
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"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.74",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
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"lessThanOrEqual": "6.18.*"
},
{
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"version": "6.19",
"versionType": "original_commit_for_fix",
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}
],
"programFiles": [
"include/linux/hugetlb.h"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-23100
Source reference:
/cveMetadata/cveId
Publisher severity
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- Event
- #27198 · Revision 1
- Added to Heist Feed
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