CVE-2026-63813

Estado: Pendiente de análisisAlta (7.8)—

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

Revert "f2fs: remove non-uptodate folio from the page cache in move_data_block"

This reverts commit 9609dd704725a40cd63d915f2ab6c44248a44598.

The kernel panics are keeping to be reported especially when the f2fs partition get almost full. By investigation, we find that the reason is one f2fs page got freed to buddy without being deleted from LRU and the root cause is the race happened in [2] which is enrolled by this commit.

There are 3 race processes in this scenario, please find below for their main activities.

The changed code in move_data_block() lets the GC path evict the tail-end folio from the page cache through folio_end_dropbehind().

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Once folio_unmap_invalidate() removes the folio from mapping->i_pages, the page-cache references for all pages in the folio are dropped. The folio is then kept alive only by temporary external references, which allows a later split to operate on a folio whose subpages are no longer protected by page-cache references.

After the page-cache references are gone, split_folio_to_order() can split the big folio into individual pages and put the resulting subpages back on the LRU. For tail pages beyond EOF, split removes them from the page cache and drops their page-cache references. A tail page can then remain on the LRU with PG_lru set while holding only the split caller's temporary reference. When free_folio_and_swap_cache() drops that final reference, the page enters the final folio_put() release path.

In parallel, folio_isolate_lru() can observe the same tail page with a non-zero refcount and PG_lru set. It clears PG_lru before taking its own reference. If this races with the final folio_put() from the split path, __folio_put() sees PG_lru already cleared and skips lruvec_del_folio(). The page is then freed back to the allocator while its lru links are still present in the LRU list. A later LRU operation on a neighboring page detects the stale link and reports list corruption.

Detalles técnicos trazas, registros y código del informe original

[1]
[   22.486082] list_del corruption. next->prev should be fffffffec10e0ac8, but was dead000000000122. (next=fffffffec10e0a88)
[   22.486130] ------------[ cut here ]------------
[   22.486134] kernel BUG at lib/list_debug.c:67!
[   22.486141] Internal error: Oops - BUG: 00000000f2000800 [#1]  SMP
[   22.488502] Tainted: [W]=WARN, [O]=OOT_MODULE
[   22.488506] Hardware name: Spreadtrum UMS9230 1H10 SoC (DT)
[   22.488511] pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[   22.488517] pc : __list_del_entry_valid_or_report+0x14c/0x154
[   22.488531] lr : __list_del_entry_valid_or_report+0x14c/0x154
[   22.488539] sp : ffffffc08006b830
[   22.488542] x29: ffffffc08006b868 x28: 0000000000003020 x27: 0000000000000000
[   22.488553] x26: 0000000000000000 x25: 0000000000000004 x24: fffffffec10e0ac0
[   22.488564] x23: 00000000000000e8 x22: 0000000000000024 x21: dead000000000122
[   22.488574] x20: fffffffec10e0a88 x19: fffffffec10e0ac8 x18: ffffffc080061060
[   22.488585] x17: 20747562202c3863 x16: 6130653031636566 x15: 0000000000000058
[   22.488595] x14: 0000000000000004 x13: ffffff80f91e0000 x12: 0000000000000003
[   22.488605] x11: 0000000000000003 x10: 0000000000000001 x9 : ffe85721f0e25f00
[   22.488615] x8 : ffe85721f0e25f00 x7 : 0000000000000000 x6 : 6c65645f7473696c
[   22.488625] x5 : ffffffed39b23026 x4 : 0000000000000000 x3 : 0000000000000010
[   22.488636] x2 : 0000000000000000 x1 : 0000000000000000 x0 : 000000000000006d
[   22.488647] Call trace:
[   22.488651]  __list_del_entry_valid_or_report+0x14c/0x154 (P)
[   22.488661]  __folio_put+0x2bc/0x434
[   22.488670]  folio_put+0x28/0x58
[   22.488678]  do_garbage_collect+0x1a34/0x2584
[   22.488689]  f2fs_gc+0x230/0x9b4
[   22.488697]  f2fs_fallocate+0xb90/0xdf4
[   22.488706]  vfs_fallocate+0x1b4/0x2bc
[   22.488716]  __arm64_sys_fallocate+0x44/0x78
[   22.488725]  invoke_syscall+0x58/0xe4
[   22.488732]  do_el0_svc+0x48/0xdc
[   22.488739]  el0
---truncated---

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Puntuación base: 7.8

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.13%
Percentil entre todas las CVEs puntuadas: 2
Fecha de la puntuación: 6/10/2026

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).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

ExplotaciónT1068 Exploitation for Privilege Escalationprivilege escalation85 %
Impacto principalT1499.004 Application or System Exploitationimpact80 %
Impacto secundarioT1561.001 Disk Content Wipeimpact70 %

Vulnerabilidad local en kernel Linux (AV:L, PR:L) que causa pánico del sistema por corrupción de memoria en LRU tras race condition. Impacto: DoS por crash del kernel y corrupción potencial del almacenamiento (partición f2fs casi llena).

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Threat Intelligence Program Filter Network Traffic Execution Prevention Application Isolation and Sandboxing Exploit Protection Update Software

Tecnologías afectadas (1)

⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.

Linux — Linux Kernel^AI

Referencias

JSON original (NVD)

Mostrar

{
  "id": "CVE-2026-63813",
  "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
      }
    ]
  },
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5a4d3968cf820686400fc757a4512dcaddd84846",
              "lessThan": "1991d49433e90b2202de2fe90be3c24161873d7c",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "9609dd704725a40cd63d915f2ab6c44248a44598",
              "lessThan": "6e035dae44154af4dd7bdb8ef7a1118c0b5f17b6",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "9609dd704725a40cd63d915f2ab6c44248a44598",
              "lessThan": "ccaba785821970f422c47770331c7e3271763f17",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "fs/f2fs/gc.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.0"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "7.0",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "7.1.3",
              "versionType": "semver",
              "lessThanOrEqual": "7.1.*"
            },
            {
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "fs/f2fs/gc.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-07-19T12:16:54.253",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/1991d49433e90b2202de2fe90be3c24161873d7c",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/6e035dae44154af4dd7bdb8ef7a1118c0b5f17b6",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/ccaba785821970f422c47770331c7e3271763f17",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Awaiting Analysis",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nRevert \"f2fs: remove non-uptodate folio from the page cache in move_data_block\"\n\nThis reverts commit 9609dd704725a40cd63d915f2ab6c44248a44598.\n\nThe kernel panics are keeping to be reported especially when the f2fs\npartition get almost full. By investigation, we find that the reason is\none f2fs page got freed to buddy without being deleted from LRU and the\nroot cause is the race happened in [2] which is enrolled by this commit.\n\nThere are 3 race processes in this scenario, please find below for their\nmain activities.\n\nThe changed code in move_data_block() lets the GC path evict the tail-end\nfolio from the page cache through folio_end_dropbehind().  Once\nfolio_unmap_invalidate() removes the folio from mapping->i_pages, the\npage-cache references for all pages in the folio are dropped.  The folio\nis then kept alive only by temporary external references, which allows a\nlater split to operate on a folio whose subpages are no longer protected\nby page-cache references.\n\nAfter the page-cache references are gone, split_folio_to_order() can\nsplit the big folio into individual pages and put the resulting subpages\nback on the LRU.  For tail pages beyond EOF, split removes them from the\npage cache and drops their page-cache references.  A tail page can then\nremain on the LRU with PG_lru set while holding only the split caller's\ntemporary reference.  When free_folio_and_swap_cache() drops that final\nreference, the page enters the final folio_put() release path.\n\nIn parallel, folio_isolate_lru() can observe the same tail page with a\nnon-zero refcount and PG_lru set.  It clears PG_lru before taking its own\nreference.  If this races with the final folio_put() from the split path,\n__folio_put() sees PG_lru already cleared and skips lruvec_del_folio().\nThe page is then freed back to the allocator while its lru links are\nstill present in the LRU list.  A later LRU operation on a neighboring\npage detects the stale link and reports list corruption.\n\n[1]\n[   22.486082] list_del corruption. next->prev should be fffffffec10e0ac8, but was dead000000000122. (next=fffffffec10e0a88)\n[   22.486130] ------------[ cut here ]------------\n[   22.486134] kernel BUG at lib/list_debug.c:67!\n[   22.486141] Internal error: Oops - BUG: 00000000f2000800 [#1]  SMP\n[   22.488502] Tainted: [W]=WARN, [O]=OOT_MODULE\n[   22.488506] Hardware name: Spreadtrum UMS9230 1H10 SoC (DT)\n[   22.488511] pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)\n[   22.488517] pc : __list_del_entry_valid_or_report+0x14c/0x154\n[   22.488531] lr : __list_del_entry_valid_or_report+0x14c/0x154\n[   22.488539] sp : ffffffc08006b830\n[   22.488542] x29: ffffffc08006b868 x28: 0000000000003020 x27: 0000000000000000\n[   22.488553] x26: 0000000000000000 x25: 0000000000000004 x24: fffffffec10e0ac0\n[   22.488564] x23: 00000000000000e8 x22: 0000000000000024 x21: dead000000000122\n[   22.488574] x20: fffffffec10e0a88 x19: fffffffec10e0ac8 x18: ffffffc080061060\n[   22.488585] x17: 20747562202c3863 x16: 6130653031636566 x15: 0000000000000058\n[   22.488595] x14: 0000000000000004 x13: ffffff80f91e0000 x12: 0000000000000003\n[   22.488605] x11: 0000000000000003 x10: 0000000000000001 x9 : ffe85721f0e25f00\n[   22.488615] x8 : ffe85721f0e25f00 x7 : 0000000000000000 x6 : 6c65645f7473696c\n[   22.488625] x5 : ffffffed39b23026 x4 : 0000000000000000 x3 : 0000000000000010\n[   22.488636] x2 : 0000000000000000 x1 : 0000000000000000 x0 : 000000000000006d\n[   22.488647] Call trace:\n[   22.488651]  __list_del_entry_valid_or_report+0x14c/0x154 (P)\n[   22.488661]  __folio_put+0x2bc/0x434\n[   22.488670]  folio_put+0x28/0x58\n[   22.488678]  do_garbage_collect+0x1a34/0x2584\n[   22.488689]  f2fs_gc+0x230/0x9b4\n[   22.488697]  f2fs_fallocate+0xb90/0xdf4\n[   22.488706]  vfs_fallocate+0x1b4/0x2bc\n[   22.488716]  __arm64_sys_fallocate+0x44/0x78\n[   22.488725]  invoke_syscall+0x58/0xe4\n[   22.488732]  do_el0_svc+0x48/0xdc\n[   22.488739]  el0\n---truncated---"
    }
  ],
  "lastModified": "2026-08-17T05:17:18.420",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}