CVE-2025-22034

Estado: ModificadaMedia (5.5)—

In the Linux kernel, the following vulnerability has been resolved:

mm/gup: reject FOLL_SPLIT_PMD with hugetlb VMAs

Patch series "mm: fixes for device-exclusive entries (hmm)", v2.

Discussing the PageTail() call in make_device_exclusive_range() with Willy, I recently discovered [1] that device-exclusive handling does not properly work with THP, making the hmm-tests selftests fail if THPs are enabled on the system.

Looking into more details, I found that hugetlb is not properly fenced, and I realized that something that was bugging me for longer -- how device-exclusive entries interact with mapcounts -- completely breaks migration/swapout/split/hwpoison handling of these folios while they have device-exclusive PTEs.

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The program below can be used to allocate 1 GiB worth of pages and making them device-exclusive on a kernel with CONFIG_TEST_HMM.

Once they are device-exclusive, these folios cannot get swapped out (proc$pid/smaps_rollup will always indicate 1 GiB RSS no matter how much one forces memory reclaim), and when having a memory block onlined to ZONE_MOVABLE, trying to offline it will loop forever and complain about failed migration of a page that should be movable.

This series fixes all issues I found so far. There is no easy way to fix without a bigger rework/cleanup. I have a bunch of cleanups on top (some previous sent, some the result of the discussion in v1) that I will send out separately once this landed and I get to it.

I wish we could just use some special present PROT_NONE PTEs instead of these (non-present, non-none) fake-swap entries; but that just results in the same problem we keep having (lack of spare PTE bits), and staring at other similar fake-swap entries, that ship has sailed.

With this series, make_device_exclusive() doesn't actually belong into mm/rmap.c anymore, but I'll leave moving that for another day.

I only tested this series with the hmm-tests selftests due to lack of HW, so I'd appreciate some testing, especially if the interaction between two GPUs wanting a device-exclusive entry works as expected.

<program> #include <stdio.h> #include <fcntl.h> #include <stdint.h> #include <unistd.h> #include <stdlib.h> #include <string.h> #include <sys/mman.h> #include <sys/ioctl.h> #include <linux/types.h> #include <linux/ioctl.h>

#define HMM_DMIRROR_EXCLUSIVE _IOWR('H', 0x05, struct hmm_dmirror_cmd)

int m ---truncated---

Detalles técnicos trazas, registros y código del informe original

# echo offline > /sys/devices/system/memory/memory136/state
# echo online_movable > /sys/devices/system/memory/memory136/state
# ./hmm-swap &
... wait until everything is device-exclusive
# echo offline > /sys/devices/system/memory/memory136/state
[  285.193431][T14882] page: refcount:2 mapcount:0 mapping:0000000000000000
  index:0x7f20671f7 pfn:0x442b6a
[  285.196618][T14882] memcg:ffff888179298000
[  285.198085][T14882] anon flags: 0x5fff0000002091c(referenced|uptodate|
  dirty|active|owner_2|swapbacked|node=1|zone=3|lastcpupid=0x7ff)
[  285.201734][T14882] raw: ...
[  285.204464][T14882] raw: ...
[  285.207196][T14882] page dumped because: migration failure
[  285.209072][T14882] page_owner tracks the page as allocated
[  285.210915][T14882] page last allocated via order 0, migratetype
  Movable, gfp_mask 0x140dca(GFP_HIGHUSER_MOVABLE|__GFP_COMP|__GFP_ZERO),
  id 14926, tgid 14926 (hmm-swap), ts 254506295376, free_ts 227402023774
[  285.216765][T14882]  post_alloc_hook+0x197/0x1b0
[  285.218874][T14882]  get_page_from_freelist+0x76e/0x3280
[  285.220864][T14882]  __alloc_frozen_pages_noprof+0x38e/0x2740
[  285.223302][T14882]  alloc_pages_mpol+0x1fc/0x540
[  285.225130][T14882]  folio_alloc_mpol_noprof+0x36/0x340
[  285.227222][T14882]  vma_alloc_folio_noprof+0xee/0x1a0
[  285.229074][T14882]  __handle_mm_fault+0x2b38/0x56a0
[  285.230822][T14882]  handle_mm_fault+0x368/0x9f0
...

struct hmm_dmirror_cmd {
	__u64 addr;
	__u64 ptr;
	__u64 npages;
	__u64 cpages;
	__u64 faults;
};

const size_t size = 1 * 1024 * 1024 * 1024ul;
const size_t chunk_size = 2 * 1024 * 1024ul;

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Puntuación base: 5.5

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.28%
Percentil entre todas las CVEs puntuadas: 18
Fecha de la puntuación: 5/10/2026

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

NVD-CWE-noinfo

Referencias

JSON original (NVD)

Mostrar

{
  "id": "CVE-2025-22034",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.8,
          "attackVector": "LOCAL",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 1.8
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              "versionType": "git"
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            {
              "status": "affected",
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              "lessThan": "8977752c8056a6a094a279004a49722da15bace3",
              "versionType": "git"
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          "programFiles": [
            "mm/gup.c"
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          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
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              "version": "6.10"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "6.10",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.12.23",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
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              "status": "unaffected",
              "version": "6.13.11",
              "versionType": "semver",
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              "version": "6.14.2",
              "versionType": "semver",
              "lessThanOrEqual": "6.14.*"
            },
            {
              "status": "unaffected",
              "version": "6.15",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "mm/gup.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2025-04-16T15:15:56.013",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/2e877ff3492267def06dd50cb165dc9ab8838e7d",
      "tags": [
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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    {
      "url": "https://git.kernel.org/stable/c/48d28417c66cce2f3b0ba773fcb6695a56eff220",
      "tags": [
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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    {
      "url": "https://git.kernel.org/stable/c/8977752c8056a6a094a279004a49722da15bace3",
      "tags": [
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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      "tags": [
        "Patch"
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "NVD-CWE-noinfo"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/gup: reject FOLL_SPLIT_PMD with hugetlb VMAs\n\nPatch series \"mm: fixes for device-exclusive entries (hmm)\", v2.\n\nDiscussing the PageTail() call in make_device_exclusive_range() with\nWilly, I recently discovered [1] that device-exclusive handling does not\nproperly work with THP, making the hmm-tests selftests fail if THPs are\nenabled on the system.\n\nLooking into more details, I found that hugetlb is not properly fenced,\nand I realized that something that was bugging me for longer -- how\ndevice-exclusive entries interact with mapcounts -- completely breaks\nmigration/swapout/split/hwpoison handling of these folios while they have\ndevice-exclusive PTEs.\n\nThe program below can be used to allocate 1 GiB worth of pages and making\nthem device-exclusive on a kernel with CONFIG_TEST_HMM.\n\nOnce they are device-exclusive, these folios cannot get swapped out\n(proc$pid/smaps_rollup will always indicate 1 GiB RSS no matter how much\none forces memory reclaim), and when having a memory block onlined to\nZONE_MOVABLE, trying to offline it will loop forever and complain about\nfailed migration of a page that should be movable.\n\n# echo offline > /sys/devices/system/memory/memory136/state\n# echo online_movable > /sys/devices/system/memory/memory136/state\n# ./hmm-swap &\n... wait until everything is device-exclusive\n# echo offline > /sys/devices/system/memory/memory136/state\n[  285.193431][T14882] page: refcount:2 mapcount:0 mapping:0000000000000000\n  index:0x7f20671f7 pfn:0x442b6a\n[  285.196618][T14882] memcg:ffff888179298000\n[  285.198085][T14882] anon flags: 0x5fff0000002091c(referenced|uptodate|\n  dirty|active|owner_2|swapbacked|node=1|zone=3|lastcpupid=0x7ff)\n[  285.201734][T14882] raw: ...\n[  285.204464][T14882] raw: ...\n[  285.207196][T14882] page dumped because: migration failure\n[  285.209072][T14882] page_owner tracks the page as allocated\n[  285.210915][T14882] page last allocated via order 0, migratetype\n  Movable, gfp_mask 0x140dca(GFP_HIGHUSER_MOVABLE|__GFP_COMP|__GFP_ZERO),\n  id 14926, tgid 14926 (hmm-swap), ts 254506295376, free_ts 227402023774\n[  285.216765][T14882]  post_alloc_hook+0x197/0x1b0\n[  285.218874][T14882]  get_page_from_freelist+0x76e/0x3280\n[  285.220864][T14882]  __alloc_frozen_pages_noprof+0x38e/0x2740\n[  285.223302][T14882]  alloc_pages_mpol+0x1fc/0x540\n[  285.225130][T14882]  folio_alloc_mpol_noprof+0x36/0x340\n[  285.227222][T14882]  vma_alloc_folio_noprof+0xee/0x1a0\n[  285.229074][T14882]  __handle_mm_fault+0x2b38/0x56a0\n[  285.230822][T14882]  handle_mm_fault+0x368/0x9f0\n...\n\nThis series fixes all issues I found so far.  There is no easy way to fix\nwithout a bigger rework/cleanup.  I have a bunch of cleanups on top (some\nprevious sent, some the result of the discussion in v1) that I will send\nout separately once this landed and I get to it.\n\nI wish we could just use some special present PROT_NONE PTEs instead of\nthese (non-present, non-none) fake-swap entries; but that just results in\nthe same problem we keep having (lack of spare PTE bits), and staring at\nother similar fake-swap entries, that ship has sailed.\n\nWith this series, make_device_exclusive() doesn't actually belong into\nmm/rmap.c anymore, but I'll leave moving that for another day.\n\nI only tested this series with the hmm-tests selftests due to lack of HW,\nso I'd appreciate some testing, especially if the interaction between two\nGPUs wanting a device-exclusive entry works as expected.\n\n<program>\n#include <stdio.h>\n#include <fcntl.h>\n#include <stdint.h>\n#include <unistd.h>\n#include <stdlib.h>\n#include <string.h>\n#include <sys/mman.h>\n#include <sys/ioctl.h>\n#include <linux/types.h>\n#include <linux/ioctl.h>\n\n#define HMM_DMIRROR_EXCLUSIVE _IOWR('H', 0x05, struct hmm_dmirror_cmd)\n\nstruct hmm_dmirror_cmd {\n\t__u64 addr;\n\t__u64 ptr;\n\t__u64 npages;\n\t__u64 cpages;\n\t__u64 faults;\n};\n\nconst size_t size = 1 * 1024 * 1024 * 1024ul;\nconst size_t chunk_size = 2 * 1024 * 1024ul;\n\nint m\n---truncated---"
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: mm/gup: rechazo de FOLL_SPLIT_PMD con VMAs hugetlb. Serie de parches \"mm: correcciones para entradas exclusivas de dispositivo (hmm)\", v2. Al hablar con Willy sobre la llamada a PageTail() en make_device_exclusive_range(), descubrí recientemente [1] que la gestión exclusiva de dispositivo no funciona correctamente con THP, lo que provoca que las autopruebas hmm-tests fallen si las THP están habilitadas en el sistema. Al analizar más a fondo, descubrí que hugetlb no está correctamente protegido y me di cuenta de que algo que me había estado molestando durante mucho tiempo (la interacción de las entradas exclusivas de dispositivo con mapcounts) interrumpe por completo la gestión de migración/intercambio/división/hwpoison de estos folios mientras tienen PTE exclusivas de dispositivo. El programa a continuación se puede usar para asignar 1 GiB de páginas y convertirlas en exclusivas de dispositivo en un kernel con CONFIG_TEST_HMM. Una vez que son exclusivos del dispositivo, estos folios no se pueden intercambiar (proc$pid/smaps_rollup siempre indicará 1 GiB RSS sin importar cuánto se fuerce la recuperación de memoria) y cuando se tiene un bloque de memoria en línea en ZONE_MOVABLE, al intentar desconectarlo se repetirá eternamente y se quejará sobre la migración fallida de una página que debería ser movible. # echo offline &gt; /sys/devices/system/memory/memory136/state # echo online_movable &gt; /sys/devices/system/memory/memory136/state # ./hmm-swap &amp; ... wait until everything is device-exclusive # echo offline &gt; /sys/devices/system/memory/memory136/state [ 285.193431][T14882] page: refcount:2 mapcount:0 mapping:0000000000000000 index:0x7f20671f7 pfn:0x442b6a [ 285.196618][T14882] memcg:ffff888179298000 [ 285.198085][T14882] anon flags: 0x5fff0000002091c(referenced|uptodate| dirty|active|owner_2|swapbacked|node=1|zone=3|lastcpupid=0x7ff) [ 285.201734][T14882] raw: ... [ 285.204464][T14882] raw: ... [ 285.207196][T14882] page dumped because: migration failure [ 285.209072][T14882] page_owner tracks the page as allocated [ 285.210915][T14882] page last allocated via order 0, migratetype Movable, gfp_mask 0x140dca(GFP_HIGHUSER_MOVABLE|__GFP_COMP|__GFP_ZERO), id 14926, tgid 14926 (hmm-swap), ts 254506295376, free_ts 227402023774 [ 285.216765][T14882] post_alloc_hook+0x197/0x1b0 [ 285.218874][T14882] get_page_from_freelist+0x76e/0x3280 [ 285.220864][T14882] __alloc_frozen_pages_noprof+0x38e/0x2740 [ 285.223302][T14882] alloc_pages_mpol+0x1fc/0x540 [ 285.225130][T14882] folio_alloc_mpol_noprof+0x36/0x340 [ 285.227222][T14882] vma_alloc_folio_noprof+0xee/0x1a0 [ 285.229074][T14882] __handle_mm_fault+0x2b38/0x56a0 [ 285.230822][T14882] handle_mm_fault+0x368/0x9f0 ... Esta serie corrige todos los problemas que he encontrado hasta ahora. No hay una solución sencilla sin una revisión o limpieza más profunda. Tengo varias correcciones adicionales (algunas enviadas previamente, otras resultantes de la discusión en la v1) que publicaré por separado una vez que esté disponible y pueda con ello. Ojalá pudiéramos usar algunas PTE PROT_NONE presentes especiales en lugar de estas entradas de intercambio falso (no presentes, no ninguna); pero eso solo resulta en el mismo problema que seguimos teniendo (falta de bits de PTE de repuesto), y al observar otras entradas de intercambio falso similares, ese barco ya pasó. Con esta serie, make_device_exclusive() ya no pertenece a mm/rmap.c, pero lo dejaré para otro día. Solo probé esta serie con las autopruebas hmm-tests debido a la falta de hardware, así que agradecería algunas pruebas, especialmente si la interacción entre dos GPU que buscan una entrada de dispositivo exclusivo funciona como se espera.  #include  #include  #include  #include  #include  #include  #include  #include  #include  #include  #define HMM_DMIRROR_EXCLUSIVE _IOWR('H', 0x05, ---truncado---"
    }
  ],
  "lastModified": "2026-07-30T06:22:04.373",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "CD08468B-6C62-4470-90F6-7F16F10CF3B4",
              "versionEndExcluding": "6.12.23",
              "versionStartIncluding": "6.10"
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "E7E864B0-8C00-4679-BA55-659B4C9C3AD3",
              "versionEndExcluding": "6.13.11",
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            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "FADAE5D8-4808-442C-B218-77B2CE8780A0",
              "versionEndExcluding": "6.14.2",
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          "operator": "OR"
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  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}