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CVE-2022-49778 (GCVE-0-2022-49778)

Vulnerability from cvelistv5 – Published: 2025-05-01 14:09 – Updated: 2026-05-11 19:06
VLAI
Title
arm64/mm: fix incorrect file_map_count for non-leaf pmd/pud
Summary
In the Linux kernel, the following vulnerability has been resolved: arm64/mm: fix incorrect file_map_count for non-leaf pmd/pud The page table check trigger BUG_ON() unexpectedly when collapse hugepage: ------------[ cut here ]------------ kernel BUG at mm/page_table_check.c:82! Internal error: Oops - BUG: 00000000f2000800 [#1] SMP Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: CPU: 6 PID: 68 Comm: khugepaged Not tainted 6.1.0-rc3+ #750 Hardware name: linux,dummy-virt (DT) pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : page_table_check_clear.isra.0+0x258/0x3f0 lr : page_table_check_clear.isra.0+0x240/0x3f0 [...] Call trace: page_table_check_clear.isra.0+0x258/0x3f0 __page_table_check_pmd_clear+0xbc/0x108 pmdp_collapse_flush+0xb0/0x160 collapse_huge_page+0xa08/0x1080 hpage_collapse_scan_pmd+0xf30/0x1590 khugepaged_scan_mm_slot.constprop.0+0x52c/0xac8 khugepaged+0x338/0x518 kthread+0x278/0x2f8 ret_from_fork+0x10/0x20 [...] Since pmd_user_accessible_page() doesn't check if a pmd is leaf, it decrease file_map_count for a non-leaf pmd comes from collapse_huge_page(). and so trigger BUG_ON() unexpectedly. Fix this problem by using pmd_leaf() insteal of pmd_present() in pmd_user_accessible_page(). Moreover, use pud_leaf() for pud_user_accessible_page() too.
Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 42b2547137f5c974bb1bfd657c869fe96b96d86f , < 2d458046df634088611d44fd77f45465e833ef78 (git)
Affected: 42b2547137f5c974bb1bfd657c869fe96b96d86f , < 5b47348fc0b18a78c96f8474cc90b7525ad1bbfe (git)
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Linux Linux Affected: 5.19
Unaffected: 0 , < 5.19 (semver)
Unaffected: 6.0.10 , ≤ 6.0.* (semver)
Unaffected: 6.1 , ≤ * (original_commit_for_fix)
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Show details on NVD website
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            "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: arm64/mm: corrige el file_map_count incorrecto para pmd/pud que no es de hoja. La comprobaci\u00f3n de la tabla de p\u00e1ginas se activa inesperadamente BUG_ON() cuando se colapsa hugepage: ------------[ cortar aqu\u00ed ]------------ \u00a1ERROR del kernel en mm/page_table_check.c:82! Error interno: Ups - BUG: 00000000f2000800 [#1] SMP Volcando b\u00fafer ftrace: (b\u00fafer ftrace vac\u00edo) M\u00f3dulos enlazados: CPU: 6 PID: 68 Comm: khugepaged No contaminado 6.1.0-rc3+ #750 Nombre del hardware: linux,dummy-virt (DT) pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : page_table_check_clear.isra.0+0x258/0x3f0 lr : page_table_check_clear.isra.0+0x240/0x3f0 [...] Rastreo de llamadas: page_table_check_clear.isra.0+0x258/0x3f0 __page_table_check_pmd_clear+0xbc/0x108 pmdp_collapse_flush+0xb0/0x160 collapse_huge_page+0xa08/0x1080 hpage_collapse_scan_pmd+0xf30/0x1590 khugepaged_scan_mm_slot.constprop.0+0x52c/0xac8 khugepaged+0x338/0x518 kthread+0x278/0x2f8 ret_from_fork+0x10/0x20 [...] Dado que pmd_user_accessible_page() no comprueba si un pmd es hoja, disminuye file_map_count para un pmd que no es hoja que proviene de colapso_huge_page() y, por lo tanto, activa BUG_ON() inesperadamente. Solucione este problema usando pmd_leaf() en lugar de pmd_present() en pmd_user_accessible_page(). Adem\u00e1s, use pud_leaf() para pud_user_accessible_page()."
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        "id": "CVE-2022-49778",
        "lastModified": "2026-06-17T05:19:07.423",
        "metrics": {
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                "attackVector": "LOCAL",
                "availabilityImpact": "HIGH",
                "baseScore": 5.5,
                "baseSeverity": "MEDIUM",
                "confidentialityImpact": "NONE",
                "integrityImpact": "NONE",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
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        "vulnStatus": "Analyzed",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-617"
              }
            ],
            "source": "nvd@nist.gov",
            "type": "Primary"
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-06-29T21:17:31+00:00",
      "cve": "CVE-2022-49778",
      "id": "CVE-2022-49778",
      "initial_release_date": "2022-01-01T00:00:00+00:00",
      "product_status:fixed": "305",
      "product_status:known_affected": "22",
      "product_status:known_not_affected": "166",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: arm64/mm: fix incorrect file_map_count for non-leaf pmd/pud",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2022/cve-2022-49778.json",
      "version": "3"
    }
  }
}



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