mm: clear uffd-wp PTE/PMD state on mremap()
In the Linux kernel, the following vulnerability has been resolved: mm: clear uffd-wp PTE/PMD state on mremap() When mremap()ing a memory region previously registered with userfaultfd as write-protected but without UFFD_FEATURE_EVENT_REMAP, an inconsistency in flag clearing leads to a mismatch between the vma flags (which have uffd-wp cleared) and the pte/pmd flags (which do not have uffd-wp cleared). This mismatch causes a subsequent mprotect(PROT_WRITE) to trigger a warning in page_table_check_pte_flags() due to setting the pte to writable while uffd-wp is still set. Fix this by always explicitly clearing the uffd-wp pte/pmd flags on any such mremap() so that the values are consistent with the existing clearing of VM_UFFD_WP. Be careful to clear the logical flag regardless of its physical form; a PTE bit, a swap PTE bit, or a PTE marker. Cover PTE, huge PMD and hugetlb paths.
CVE-2025-21696
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-2025-21696
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": "63b2d4174c4ad1f40b48d7138e71bcb564c1fe03",
"lessThan": "8e2f6ba256dd1e590addc48e6e9577bf39c482f2",
"versionType": "git"
},
{
"status": "affected",
"version": "63b2d4174c4ad1f40b48d7138e71bcb564c1fe03",
"lessThan": "310ac886d68de661c3a334198d8604b722d7fdf8",
"versionType": "git"
},
{
"status": "affected",
"version": "63b2d4174c4ad1f40b48d7138e71bcb564c1fe03",
"lessThan": "0cef0bb836e3cfe00f08f9606c72abd72fe78ca3",
"versionType": "git"
}
],
"programFiles": [
"include/linux/userfaultfd_k.h",
"mm/huge_memory.c",
"mm/hugetlb.c",
"mm/mremap.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "5.7"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "5.7",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.6.160",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.11",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.13",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"include/linux/userfaultfd_k.h",
"mm/huge_memory.c",
"mm/hugetlb.c",
"mm/mremap.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2025-21696
Source reference:
/cveMetadata/cveId
Publisher severity
No explicit severity was provided.
- Event
- #45939 · Revision 1
- Added to Heist Feed
- Publisher date