CVE-2025-21778

Estado: ModificadaMedia (5.5)—

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

tracing: Do not allow mmap() of persistent ring buffer

When trying to mmap a trace instance buffer that is attached to reserve_mem, it would crash:

The reason was that the code that maps the ring buffer pages to user space has:

And uses that in:

But virt_to_page() does not work with vmap()'d memory which is what the persistent ring buffer has. It is rather trivial to allow this, but for now just disable mmap() of instances that have their ring buffer from the reserve_mem option.

If an mmap() is performed on a persistent buffer it will return -ENODEV just like it would if the .mmap field wasn't defined in the file_operations structure.

Detalles técnicos trazas, registros y código del informe original

 BUG: unable to handle page fault for address: ffffe97bd00025c8
 #PF: supervisor read access in kernel mode
 #PF: error_code(0x0000) - not-present page
 PGD 2862f3067 P4D 2862f3067 PUD 0
 Oops: Oops: 0000 [#1] PREEMPT_RT SMP PTI
 CPU: 4 UID: 0 PID: 981 Comm: mmap-rb Not tainted 6.14.0-rc2-test-00003-g7f1a5e3fbf9e-dirty #233
 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
 RIP: 0010:validate_page_before_insert+0x5/0xb0
 Code: e2 01 89 d0 c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 <48> 8b 46 08 a8 01 75 67 66 90 48 89 f0 8b 50 34 85 d2 74 76 48 89
 RSP: 0018:ffffb148c2f3f968 EFLAGS: 00010246
 RAX: ffff9fa5d3322000 RBX: ffff9fa5ccff9c08 RCX: 00000000b879ed29
 RDX: ffffe97bd00025c0 RSI: ffffe97bd00025c0 RDI: ffff9fa5ccff9c08
 RBP: ffffb148c2f3f9f0 R08: 0000000000000004 R09: 0000000000000004
 R10: 0000000000000000 R11: 0000000000000200 R12: 0000000000000000
 R13: 00007f16a18d5000 R14: ffff9fa5c48db6a8 R15: 0000000000000000
 FS:  00007f16a1b54740(0000) GS:ffff9fa73df00000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: ffffe97bd00025c8 CR3: 00000001048c6006 CR4: 0000000000172ef0
 Call Trace:
  <TASK>
  ? __die_body.cold+0x19/0x1f
  ? __die+0x2e/0x40
  ? page_fault_oops+0x157/0x2b0
  ? search_module_extables+0x53/0x80
  ? validate_page_before_insert+0x5/0xb0
  ? kernelmode_fixup_or_oops.isra.0+0x5f/0x70
  ? __bad_area_nosemaphore+0x16e/0x1b0
  ? bad_area_nosemaphore+0x16/0x20
  ? do_kern_addr_fault+0x77/0x90
  ? exc_page_fault+0x22b/0x230
  ? asm_exc_page_fault+0x2b/0x30
  ? validate_page_before_insert+0x5/0xb0
  ? vm_insert_pages+0x151/0x400
  __rb_map_vma+0x21f/0x3f0
  ring_buffer_map+0x21b/0x2f0
  tracing_buffers_mmap+0x70/0xd0
  __mmap_region+0x6f0/0xbd0
  mmap_region+0x7f/0x130
  do_mmap+0x475/0x610
  vm_mmap_pgoff+0xf2/0x1d0
  ksys_mmap_pgoff+0x166/0x200
  __x64_sys_mmap+0x37/0x50
  x64_sys_call+0x1670/0x1d70
  do_syscall_64+0xbb/0x1d0
  entry_SYSCALL_64_after_hwframe+0x77/0x7f

	page = virt_to_page((void *)cpu_buffer->subbuf_ids[s]);

	vm_insert_pages(vma, vma->vm_start, pages, &nr_pages);

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: 0.22%
Percentil entre todas las CVEs puntuadas: 11
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).

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

NVD-CWE-noinfo

Referencias

JSON original (NVD)

Mostrar

{
  "id": "CVE-2025-21778",
  "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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        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 5.5,
          "attackVector": "LOCAL",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 1.8
      }
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  "affected": [
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "9b7bdf6f6ece6ea888cc7d2f02c00b403b66a119",
              "lessThan": "e8dff5f73912513fc9b52ab992d861517c9a9975",
              "versionType": "git"
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            {
              "status": "affected",
              "version": "9b7bdf6f6ece6ea888cc7d2f02c00b403b66a119",
              "lessThan": "cf5aa560e5c7628b57c928741d7e6a9a0f6f0e67",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "9b7bdf6f6ece6ea888cc7d2f02c00b403b66a119",
              "lessThan": "129fe718819cc5e24ea2f489db9ccd4371f0c6f6",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "kernel/trace/trace.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.12"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "6.12",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.12.16",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.13.4",
              "versionType": "semver",
              "lessThanOrEqual": "6.13.*"
            },
            {
              "status": "unaffected",
              "version": "6.14",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "kernel/trace/trace.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2025-02-27T03:15:18.533",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/129fe718819cc5e24ea2f489db9ccd4371f0c6f6",
      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/cf5aa560e5c7628b57c928741d7e6a9a0f6f0e67",
      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/e8dff5f73912513fc9b52ab992d861517c9a9975",
      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "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\ntracing: Do not allow mmap() of persistent ring buffer\n\nWhen trying to mmap a trace instance buffer that is attached to\nreserve_mem, it would crash:\n\n BUG: unable to handle page fault for address: ffffe97bd00025c8\n #PF: supervisor read access in kernel mode\n #PF: error_code(0x0000) - not-present page\n PGD 2862f3067 P4D 2862f3067 PUD 0\n Oops: Oops: 0000 [#1] PREEMPT_RT SMP PTI\n CPU: 4 UID: 0 PID: 981 Comm: mmap-rb Not tainted 6.14.0-rc2-test-00003-g7f1a5e3fbf9e-dirty #233\n Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014\n RIP: 0010:validate_page_before_insert+0x5/0xb0\n Code: e2 01 89 d0 c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 <48> 8b 46 08 a8 01 75 67 66 90 48 89 f0 8b 50 34 85 d2 74 76 48 89\n RSP: 0018:ffffb148c2f3f968 EFLAGS: 00010246\n RAX: ffff9fa5d3322000 RBX: ffff9fa5ccff9c08 RCX: 00000000b879ed29\n RDX: ffffe97bd00025c0 RSI: ffffe97bd00025c0 RDI: ffff9fa5ccff9c08\n RBP: ffffb148c2f3f9f0 R08: 0000000000000004 R09: 0000000000000004\n R10: 0000000000000000 R11: 0000000000000200 R12: 0000000000000000\n R13: 00007f16a18d5000 R14: ffff9fa5c48db6a8 R15: 0000000000000000\n FS:  00007f16a1b54740(0000) GS:ffff9fa73df00000(0000) knlGS:0000000000000000\n CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n CR2: ffffe97bd00025c8 CR3: 00000001048c6006 CR4: 0000000000172ef0\n Call Trace:\n  <TASK>\n  ? __die_body.cold+0x19/0x1f\n  ? __die+0x2e/0x40\n  ? page_fault_oops+0x157/0x2b0\n  ? search_module_extables+0x53/0x80\n  ? validate_page_before_insert+0x5/0xb0\n  ? kernelmode_fixup_or_oops.isra.0+0x5f/0x70\n  ? __bad_area_nosemaphore+0x16e/0x1b0\n  ? bad_area_nosemaphore+0x16/0x20\n  ? do_kern_addr_fault+0x77/0x90\n  ? exc_page_fault+0x22b/0x230\n  ? asm_exc_page_fault+0x2b/0x30\n  ? validate_page_before_insert+0x5/0xb0\n  ? vm_insert_pages+0x151/0x400\n  __rb_map_vma+0x21f/0x3f0\n  ring_buffer_map+0x21b/0x2f0\n  tracing_buffers_mmap+0x70/0xd0\n  __mmap_region+0x6f0/0xbd0\n  mmap_region+0x7f/0x130\n  do_mmap+0x475/0x610\n  vm_mmap_pgoff+0xf2/0x1d0\n  ksys_mmap_pgoff+0x166/0x200\n  __x64_sys_mmap+0x37/0x50\n  x64_sys_call+0x1670/0x1d70\n  do_syscall_64+0xbb/0x1d0\n  entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nThe reason was that the code that maps the ring buffer pages to user space\nhas:\n\n\tpage = virt_to_page((void *)cpu_buffer->subbuf_ids[s]);\n\nAnd uses that in:\n\n\tvm_insert_pages(vma, vma->vm_start, pages, &nr_pages);\n\nBut virt_to_page() does not work with vmap()'d memory which is what the\npersistent ring buffer has. It is rather trivial to allow this, but for\nnow just disable mmap() of instances that have their ring buffer from the\nreserve_mem option.\n\nIf an mmap() is performed on a persistent buffer it will return -ENODEV\njust like it would if the .mmap field wasn't defined in the\nfile_operations structure."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: tracing: No permitir mmap() de búfer de anillo persistente Al intentar mmap un búfer de instancia de seguimiento que está adjunto a reserve_mem, se bloquearía: BUG: no se puede manejar el error de página para la dirección: ffffe97bd00025c8 #PF: acceso de lectura de supervisor en modo kernel #PF: error_code(0x0000) - página no presente PGD 2862f3067 P4D 2862f3067 PUD 0 Oops: Oops: 0000 [#1] PREEMPT_RT SMP PTI CPU: 4 UID: 0 PID: 981 Comm: mmap-rb No contaminado 6.14.0-rc2-test-00003-g7f1a5e3fbf9e-dirty #233 Nombre del hardware: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 01/04/2014 RIP: 0010:validate_page_before_insert+0x5/0xb0 Código: e2 01 89 d0 c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 &lt;48&gt; 8b 46 08 a8 01 75 67 66 90 48 89 f0 8b 50 34 85 d2 74 76 48 89 RSP: 0018:ffffb148c2f3f968 EFLAGS: 00010246 RAX: ffff9fa5d3322000 RBX: ffff9fa5ccff9c08 RCX: 00000000b879ed29 RDX: ffffe97bd00025c0 RSI: ffffe97bd00025c0 RDI: ffff9fa5ccff9c08 RBP: ffffb148c2f3f9f0 R08: 000000000000004 R09: 0000000000000004 R10: 0000000000000000 R11: 0000000000000200 R12: 0000000000000000 R13: 00007f16a18d5000 R14: ffff9fa5c48db6a8 R15: 0000000000000000 FS: 00007f16a1b54740(0000) GS:ffff9fa73df00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000080050033 CR2: ffffe97bd00025c8 CR3: 00000001048c6006 CR4: 0000000000172ef0 Seguimiento de llamadas:  ? __die_body.cold+0x19/0x1f ? __die+0x2e/0x40 ? page_fault_oops+0x157/0x2b0 ? search_module_extables+0x53/0x80 ? validation_page_before_insert+0x5/0xb0 ? kernelmode_fixup_or_oops.isra.0+0x5f/0x70 ? __bad_area_nosemaphore+0x16e/0x1b0 ? bad_area_nosemaphore+0x16/0x20 ? do_kern_addr_fault+0x77/0x90 ? exc_page_fault+0x22b/0x230 ? asm_exc_page_fault+0x2b/0x30 ? validate_page_before_insert+0x5/0xb0 ? vm_insert_pages+0x151/0x400 __rb_map_vma+0x21f/0x3f0 ring_buffer_map+0x21b/0x2f0 tracing_buffers_mmap+0x70/0xd0 __mmap_region+0x6f0/0xbd0 mmap_region+0x7f/0x130 do_mmap+0x475/0x610 vm_mmap_pgoff+0xf2/0x1d0 ksys_mmap_pgoff+0x166/0x200 __x64_sys_mmap+0x37/0x50 x64_sys_call+0x1670/0x1d70 do_syscall_64+0xbb/0x1d0 entry_SYSCALL_64_after_hwframe+0x77/0x7f La razón fue que el código que asigna las páginas del búfer de anillo al espacio de usuario tiene: page = virt_to_page((void *)cpu_buffer-&gt;subbuf_ids[s]); Y lo usa en: vm_insert_pages(vma, vma-&gt;vm_start, pages, &amp;nr_pages); Pero virt_to_page() no funciona con la memoria vmap() que es la que tiene el búfer de anillo persistente. Es bastante trivial permitir esto, pero por ahora simplemente deshabilite mmap() de las instancias que tienen su búfer de anillo desde la opción reserve_mem. Si se realiza un mmap() en un búfer persistente, devolverá -ENODEV tal como lo haría si el campo .mmap no estuviera definido en la estructura file_operations."
    }
  ],
  "lastModified": "2026-07-30T06:21:30.240",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "537F3B42-2EC5-47FB-8166-5ACF0353AFEC",
              "versionEndExcluding": "6.12.16",
              "versionStartIncluding": "6.12"
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "2A2093ED-74A9-43F9-AC72-50030F374EA4",
              "versionEndExcluding": "6.13.4",
              "versionStartIncluding": "6.13"
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc1:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "186716B6-2B66-4BD0-852E-D48E71C0C85F"
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc2:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "0D3E781C-403A-498F-9DA9-ECEE50F41E75"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}