CVE-2025-38084

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2025-38084", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T04:51:23.981Z", "datePublished": "2025-06-28T07:44:25.379Z", "dateUpdated": "2026-10-15T21:52:07.643Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:59:22.391Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/hugetlb: unshare page tables during VMA split, not before\n\nCurrently, __split_vma() triggers hugetlb page table unsharing through\nvm_ops->may_split(). This happens before the VMA lock and rmap locks are\ntaken - which is too early, it allows racing VMA-locked page faults in our\nprocess and racing rmap walks from other processes to cause page tables to\nbe shared again before we actually perform the split.\n\nFix it by explicitly calling into the hugetlb unshare logic from\n__split_vma() in the same place where THP splitting also happens. At that\npoint, both the VMA and the rmap(s) are write-locked.\n\nAn annoying detail is that we can now call into the helper\nhugetlb_unshare_pmds() from two different locking contexts:\n\n1. from hugetlb_split(), holding:\n - mmap lock (exclusively)\n - VMA lock\n - file rmap lock (exclusively)\n2. hugetlb_unshare_all_pmds(), which I think is designed to be able to\n call us with only the mmap lock held (in shared mode), but currently\n only runs while holding mmap lock (exclusively) and VMA lock\n\nBackporting note:\nThis commit fixes a racy protection that was introduced in commit\nb30c14cd6102 (\"hugetlb: unshare some PMDs when splitting VMAs\"); that\ncommit claimed to fix an issue introduced in 5.13, but it should actually\nalso go all the way back.\n\n[jannh@google.com: v2]"}], "metrics": [{"cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH"}, "scenarios": [{"lang": "en", "value": "AV:L - The race is driven entirely through local syscalls \u2014 `mmap(MAP_SHARED|MAP_HUGETLB)` plus `munmap`/`mprotect`/`madvise` to force a non-PUD-aligned `__split_vma()`, with concurrent threads faulting the mapping. No network or physical component is involved.\nAC:L - The attacker controls both sides of the race and the window is very wide \u2014 several sleeping GFP_KERNEL allocations sit between `may_split()` and `vma_start_write()` \u2014 and it can be retried indefinitely and widened with memory pressure. PMD sharing is compiled in by default on x86_64/arm64/riscv64, and the only environmental dependency (preallocated hugepages) is standard in the KVM/cloud, database and DPDK deployments this code targets.\nPR:L - An ordinary unprivileged user can create the required VM_MAYSHARE hugetlb mapping, because `mmap(MAP_ANONYMOUS|MAP_HUGETLB)` uses `HUGETLB_ANONHUGE_INODE` and therefore bypasses the `can_do_hugetlb_shm()`/`CAP_IPC_LOCK` check that guards SysV `SHM_HUGETLB`; `fork()` supplies the second sharing VMA. No capability is needed for the splitting syscalls either.\nUI:N - The whole sequence is performed programmatically by the attacker's own multi-threaded process; no victim action or interaction is required.\nS:U - The corrupted page tables belong to the attacking process's own mm within the host kernel's security authority, so this is standard local kernel compromise rather than a crossing of a VM/IOMMU boundary.\nC:H - A freed page-table page that is still referenced by a live PUD entry is the classic \"dirty pagetable\" primitive \u2014 once reallocated, the attacker can read arbitrary physical memory, disclosing kernel data and other processes' memory in full.\nI:H - The same page-table UAF yields an arbitrary physical-memory write primitive (writing PTEs into a reused page table), enabling kernel data modification, credential overwrite and full privilege escalation; it also leaves dangling KVM MMU mappings.\nA:H - Use-after-free of page tables reliably corrupts the memory management state, producing oopses, BUG_ON hits and kernel panics even in unsuccessful exploitation attempts, and it can be triggered repeatedly."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["include/linux/hugetlb.h", "mm/hugetlb.c", "mm/vma.c", "tools/testing/vma/vma_internal.h"], "versions": [{"version": "39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa", "lessThan": "e8847d18cd9fff1edbb45e963d9141273c3b539c", "status": "affected", "versionType": "git"}, {"version": "39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa", "lessThan": "366298f2b04d2bf1f2f2b7078405bdf9df9bd5d0", "status": "affected", "versionType": "git"}, {"version": "39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa", "lessThan": "2511ac64bc1617ca716d3ba8464e481a647c1902", "status": "affected", "versionType": "git"}, {"version": "39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa", "lessThan": "af6cfcd0efb7f051af221c418ec8b37a10211947", "status": "affected", "versionType": "git"}, {"version": "39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa", "lessThan": "9cf5b2a3b72c23fb7b84736d5d19ee6ea718762b", "status": "affected", "versionType": "git"}, {"version": "39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa", "lessThan": "8a21d5584826f4880f45bbf8f72375f4e6c0ff2a", "status": "affected", "versionType": "git"}, {"version": "39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa", "lessThan": "081056dc00a27bccb55ccc3c6f230a3d5fd3f7e0", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["include/linux/hugetlb.h", "mm/hugetlb.c", "mm/vma.c", "tools/testing/vma/vma_internal.h"], "versions": [{"version": "2.6.20", "status": "affected"}, {"version": "0", "lessThan": "2.6.20", "status": "unaffected", "versionType": "semver"}, {"version": "5.10.239", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.15.186", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.142", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.95", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.35", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.15.4", "lessThanOrEqual": "6.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.16", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.20", "versionEndExcluding": "5.10.239"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.20", "versionEndExcluding": "5.15.186"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.20", "versionEndExcluding": "6.1.142"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.20", "versionEndExcluding": "6.6.95"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.20", "versionEndExcluding": "6.12.35"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.20", "versionEndExcluding": "6.15.4"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.20", "versionEndExcluding": "6.16"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/e8847d18cd9fff1edbb45e963d9141273c3b539c"}, {"url": "https://git.kernel.org/stable/c/366298f2b04d2bf1f2f2b7078405bdf9df9bd5d0"}, {"url": "https://git.kernel.org/stable/c/2511ac64bc1617ca716d3ba8464e481a647c1902"}, {"url": "https://git.kernel.org/stable/c/af6cfcd0efb7f051af221c418ec8b37a10211947"}, {"url": "https://git.kernel.org/stable/c/9cf5b2a3b72c23fb7b84736d5d19ee6ea718762b"}, {"url": "https://git.kernel.org/stable/c/8a21d5584826f4880f45bbf8f72375f4e6c0ff2a"}, {"url": "https://git.kernel.org/stable/c/081056dc00a27bccb55ccc3c6f230a3d5fd3f7e0"}, {"url": "https://project-zero.issues.chromium.org/issues/420715744"}], "title": "mm/hugetlb: unshare page tables during VMA split, not before", "x_generator": {"engine": "bippy-1.2.0"}}, "adp": [{"title": "CVE Program Container", "references": [{"url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html"}, {"url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html"}], "providerMetadata": {"orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T17:33:52.441Z"}}, {"metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2025-38084", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2026-10-15T21:47:11.964385Z"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-15T21:52:07.643Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CVE Program Container", "references": [{"url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html"}, {"url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html"}], "providerMetadata": {"orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T17:33:52.441Z"}}, {"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2025-38084", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2026-10-15T21:47:11.964385Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-15T21:47:12.468Z"}}], "cna": {"title": "mm/hugetlb: unshare page tables during VMA split, not before", "metrics": [{"cvssV3_1": {"version": "3.1", "baseScore": 7.8, "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}, "scenarios": [{"lang": "en", "value": "AV:L - The race is driven entirely through local syscalls \u2014 `mmap(MAP_SHARED|MAP_HUGETLB)` plus `munmap`/`mprotect`/`madvise` to force a non-PUD-aligned `__split_vma()`, with concurrent threads faulting the mapping. No network or physical component is involved.\nAC:L - The attacker controls both sides of the race and the window is very wide \u2014 several sleeping GFP_KERNEL allocations sit between `may_split()` and `vma_start_write()` \u2014 and it can be retried indefinitely and widened with memory pressure. PMD sharing is compiled in by default on x86_64/arm64/riscv64, and the only environmental dependency (preallocated hugepages) is standard in the KVM/cloud, database and DPDK deployments this code targets.\nPR:L - An ordinary unprivileged user can create the required VM_MAYSHARE hugetlb mapping, because `mmap(MAP_ANONYMOUS|MAP_HUGETLB)` uses `HUGETLB_ANONHUGE_INODE` and therefore bypasses the `can_do_hugetlb_shm()`/`CAP_IPC_LOCK` check that guards SysV `SHM_HUGETLB`; `fork()` supplies the second sharing VMA. No capability is needed for the splitting syscalls either.\nUI:N - The whole sequence is performed programmatically by the attacker's own multi-threaded process; no victim action or interaction is required.\nS:U - The corrupted page tables belong to the attacking process's own mm within the host kernel's security authority, so this is standard local kernel compromise rather than a crossing of a VM/IOMMU boundary.\nC:H - A freed page-table page that is still referenced by a live PUD entry is the classic \"dirty pagetable\" primitive \u2014 once reallocated, the attacker can read arbitrary physical memory, disclosing kernel data and other processes' memory in full.\nI:H - The same page-table UAF yields an arbitrary physical-memory write primitive (writing PTEs into a reused page table), enabling kernel data modification, credential overwrite and full privilege escalation; it also leaves dangling KVM MMU mappings.\nA:H - Use-after-free of page tables reliably corrupts the memory management state, producing oopses, BUG_ON hits and kernel panics even in unsuccessful exploitation attempts, and it can be triggered repeatedly."}]}], "affected": [{"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa", "lessThan": "e8847d18cd9fff1edbb45e963d9141273c3b539c", "versionType": "git"}, {"status": "affected", "version": "39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa", "lessThan": "366298f2b04d2bf1f2f2b7078405bdf9df9bd5d0", "versionType": "git"}, {"status": "affected", "version": "39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa", "lessThan": "2511ac64bc1617ca716d3ba8464e481a647c1902", "versionType": "git"}, {"status": "affected", "version": "39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa", "lessThan": "af6cfcd0efb7f051af221c418ec8b37a10211947", "versionType": "git"}, {"status": "affected", "version": "39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa", "lessThan": "9cf5b2a3b72c23fb7b84736d5d19ee6ea718762b", "versionType": "git"}, {"status": "affected", "version": "39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa", "lessThan": "8a21d5584826f4880f45bbf8f72375f4e6c0ff2a", "versionType": "git"}, {"status": "affected", "version": "39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa", "lessThan": "081056dc00a27bccb55ccc3c6f230a3d5fd3f7e0", "versionType": "git"}], "programFiles": ["include/linux/hugetlb.h", "mm/hugetlb.c", "mm/vma.c", "tools/testing/vma/vma_internal.h"], "defaultStatus": "unaffected"}, {"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "2.6.20"}, {"status": "unaffected", "version": "0", "lessThan": "2.6.20", "versionType": "semver"}, {"status": "unaffected", "version": "5.10.239", "versionType": "semver", "lessThanOrEqual": "5.10.*"}, {"status": "unaffected", "version": "5.15.186", "versionType": "semver", "lessThanOrEqual": "5.15.*"}, {"status": "unaffected", "version": "6.1.142", "versionType": "semver", "lessThanOrEqual": "6.1.*"}, {"status": "unaffected", "version": "6.6.95", "versionType": "semver", "lessThanOrEqual": "6.6.*"}, {"status": "unaffected", "version": "6.12.35", "versionType": "semver", "lessThanOrEqual": "6.12.*"}, {"status": "unaffected", "version": "6.15.4", "versionType": "semver", "lessThanOrEqual": "6.15.*"}, {"status": "unaffected", "version": "6.16", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*"}], "programFiles": ["include/linux/hugetlb.h", "mm/hugetlb.c", "mm/vma.c", "tools/testing/vma/vma_internal.h"], "defaultStatus": "affected"}], "references": [{"url": "https://git.kernel.org/stable/c/e8847d18cd9fff1edbb45e963d9141273c3b539c"}, {"url": "https://git.kernel.org/stable/c/366298f2b04d2bf1f2f2b7078405bdf9df9bd5d0"}, {"url": "https://git.kernel.org/stable/c/2511ac64bc1617ca716d3ba8464e481a647c1902"}, {"url": "https://git.kernel.org/stable/c/af6cfcd0efb7f051af221c418ec8b37a10211947"}, {"url": "https://git.kernel.org/stable/c/9cf5b2a3b72c23fb7b84736d5d19ee6ea718762b"}, {"url": "https://git.kernel.org/stable/c/8a21d5584826f4880f45bbf8f72375f4e6c0ff2a"}, {"url": "https://git.kernel.org/stable/c/081056dc00a27bccb55ccc3c6f230a3d5fd3f7e0"}, {"url": "https://project-zero.issues.chromium.org/issues/420715744"}], "x_generator": {"engine": "bippy-1.2.0"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/hugetlb: unshare page tables during VMA split, not before\n\nCurrently, __split_vma() triggers hugetlb page table unsharing through\nvm_ops->may_split(). This happens before the VMA lock and rmap locks are\ntaken - which is too early, it allows racing VMA-locked page faults in our\nprocess and racing rmap walks from other processes to cause page tables to\nbe shared again before we actually perform the split.\n\nFix it by explicitly calling into the hugetlb unshare logic from\n__split_vma() in the same place where THP splitting also happens. At that\npoint, both the VMA and the rmap(s) are write-locked.\n\nAn annoying detail is that we can now call into the helper\nhugetlb_unshare_pmds() from two different locking contexts:\n\n1. from hugetlb_split(), holding:\n - mmap lock (exclusively)\n - VMA lock\n - file rmap lock (exclusively)\n2. hugetlb_unshare_all_pmds(), which I think is designed to be able to\n call us with only the mmap lock held (in shared mode), but currently\n only runs while holding mmap lock (exclusively) and VMA lock\n\nBackporting note:\nThis commit fixes a racy protection that was introduced in commit\nb30c14cd6102 (\"hugetlb: unshare some PMDs when splitting VMAs\"); that\ncommit claimed to fix an issue introduced in 5.13, but it should actually\nalso go all the way back.\n\n[jannh@google.com: v2]"}], "cpeApplicability": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "5.10.239", "versionStartIncluding": "2.6.20"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "5.15.186", "versionStartIncluding": "2.6.20"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.1.142", "versionStartIncluding": "2.6.20"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.6.95", "versionStartIncluding": "2.6.20"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.12.35", "versionStartIncluding": "2.6.20"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.15.4", "versionStartIncluding": "2.6.20"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.16", "versionStartIncluding": "2.6.20"}], "operator": "OR"}]}], "providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:59:22.391Z"}}}, "cveMetadata": {"cveId": "CVE-2025-38084", "state": "PUBLISHED", "dateUpdated": "2026-10-15T21:52:07.643Z", "dateReserved": "2025-04-16T04:51:23.981Z", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "datePublished": "2025-06-28T07:44:25.379Z", "assignerShortName": "Linux"}, "dataVersion": "5.2"}

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This happens before the VMA lock and rmap locks are\ntaken - which is too early, it allows racing VMA-locked page faults in our\nprocess and racing rmap walks from other processes to cause page tables to\nbe shared again before we actually perform the split.\n\nFix it by explicitly calling into the hugetlb unshare logic from\n__split_vma() in the same place where THP splitting also happens. At that\npoint, both the VMA and the rmap(s) are write-locked.\n\nAn annoying detail is that we can now call into the helper\nhugetlb_unshare_pmds() from two different locking contexts:\n\n1. from hugetlb_split(), holding:\n - mmap lock (exclusively)\n - VMA lock\n - file rmap lock (exclusively)\n2. hugetlb_unshare_all_pmds(), which I think is designed to be able to\n call us with only the mmap lock held (in shared mode), but currently\n only runs while holding mmap lock (exclusively) and VMA lock\n\nBackporting note:\nThis commit fixes a racy protection that was introduced in commit\nb30c14cd6102 (\"hugetlb: unshare some PMDs when splitting VMAs\"); that\ncommit claimed to fix an issue introduced in 5.13, but it should actually\nalso go all the way back.\n\n[jannh@google.com: v2]"}, {"lang": "es", "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: mm/hugetlb: dejar de compartir tablas de p\u00e1ginas durante la divisi\u00f3n de VMA, no antes. Actualmente, __split_vma() activa la descompartici\u00f3n de la tabla de p\u00e1ginas hugetlb a trav\u00e9s de vm_ops->may_split(). Esto sucede antes de que se tomen los bloqueos de VMA y rmap, lo cual es demasiado pronto, ya que permite que las fallas de p\u00e1gina bloqueadas por VMA en nuestro proceso y los recorridos rmap de otros procesos provoquen que las tablas de p\u00e1ginas se compartan de nuevo antes de que realmente realicemos la divisi\u00f3n. Corr\u00edjalo llamando expl\u00edcitamente a la l\u00f3gica de descompartir hugetlb desde __split_vma() en el mismo lugar donde tambi\u00e9n ocurre la divisi\u00f3n de THP. En ese punto, tanto el VMA como los rmap est\u00e1n bloqueados contra escritura. Un detalle molesto es que ahora podemos llamar al asistente hugetlb_unshare_pmds() desde dos contextos de bloqueo diferentes: 1. desde hugetlb_split(), que contiene: - bloqueo mmap (exclusivamente) - bloqueo VMA - bloqueo rmap de archivo (exclusivamente) 2. hugetlb_unshare_all_pmds(), que creo que est\u00e1 dise\u00f1ado para poder llamarnos con solo el bloqueo mmap mantenido (en modo compartido), pero actualmente solo se ejecuta mientras se mantiene el bloqueo mmap (exclusivamente) y el bloqueo VMA. Nota de retroportaci\u00f3n: Este commit corrige una protecci\u00f3n contra la exposici\u00f3n a riesgos que se introdujo en el commit b30c14cd6102 (\"hugetlb: dejar de compartir algunos PMD al dividir VMA\"); es commit afirmaba corregir un problema introducido en la versi\u00f3n 5.13, pero en realidad tambi\u00e9n deber\u00eda retroceder. [jannh@google.com: v2]"}], "id": "CVE-2025-38084", "lastModified": "2026-10-15T22:18:26.120", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 5.9, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}, {"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 5.5, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 3.6, "source": "nvd@nist.gov", "type": "Primary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2025-38084", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-10-15T21:47:11.964385Z", "version": "2.0.3"}}]}, "published": "2025-06-28T08:15:23.970", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/081056dc00a27bccb55ccc3c6f230a3d5fd3f7e0"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/2511ac64bc1617ca716d3ba8464e481a647c1902"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/366298f2b04d2bf1f2f2b7078405bdf9df9bd5d0"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/8a21d5584826f4880f45bbf8f72375f4e6c0ff2a"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/9cf5b2a3b72c23fb7b84736d5d19ee6ea718762b"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/af6cfcd0efb7f051af221c418ec8b37a10211947"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/e8847d18cd9fff1edbb45e963d9141273c3b539c"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Third Party Advisory"], "url": "https://project-zero.issues.chromium.org/issues/420715744"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Third Party Advisory"], "url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Third Party Advisory"], "url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Modified", "weaknesses": [{"description": [{"lang": "en", "value": "NVD-CWE-noinfo"}], "source": "nvd@nist.gov", "type": "Primary"}]}

{"bugzilla": {"description": "kernel: mm/hugetlb: unshare page tables during VMA split, not before", "id": "2375303", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2375303"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.1", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H", "status": "draft"}, "cwe": "CWE-200", "details": ["In the Linux kernel, the following vulnerability has been resolved:\nmm/hugetlb: unshare page tables during VMA split, not before\nCurrently, __split_vma() triggers hugetlb page table unsharing through\nvm_ops->may_split(). This happens before the VMA lock and rmap locks are\ntaken - which is too early, it allows racing VMA-locked page faults in our\nprocess and racing rmap walks from other processes to cause page tables to\nbe shared again before we actually perform the split.\nFix it by explicitly calling into the hugetlb unshare logic from\n__split_vma() in the same place where THP splitting also happens. At that\npoint, both the VMA and the rmap(s) are write-locked.\nAn annoying detail is that we can now call into the helper\nhugetlb_unshare_pmds() from two different locking contexts:\n1. from hugetlb_split(), holding:\n- mmap lock (exclusively)\n- VMA lock\n- file rmap lock (exclusively)\n2. hugetlb_unshare_all_pmds(), which I think is designed to be able to\ncall us with only the mmap lock held (in shared mode), but currently\nonly runs while holding mmap lock (exclusively) and VMA lock\nBackporting note:\nThis commit fixes a racy protection that was introduced in commit\nb30c14cd6102 (\"hugetlb: unshare some PMDs when splitting VMAs\"); that\ncommit claimed to fix an issue introduced in 5.13, but it should actually\nalso go all the way back.\n[jannh@google.com: v2]"], "name": "CVE-2025-38084", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Under investigation", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Under investigation", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2025-06-28T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2025-38084\nhttps://nvd.nist.gov/vuln/detail/CVE-2025-38084\nhttps://lore.kernel.org/linux-cve-announce/2025062834-CVE-2025-38084-9121@gregkh/T"], "threat_severity": "Moderate"}

{"created": "2025-07-06T22:16:28.351838+00:00", "updated": "2025-07-06T22:16:28.351887+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}