« Volver al listado

CVE-2025-37807

Estado: AnalizadaMedia (5.5)—

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

bpf: Fix kmemleak warning for percpu hashmap

Vlad Poenaru reported the following kmemleak issue:

Further investigation shows the reason is due to not 8-byte aligned store of percpu pointer in htab_elem_set_ptr(): *(void __percpu **)(l->key + key_size) = pptr;

Note that the whole htab_elem alignment is 8 (for x86_64). If the key_size is 4, that means pptr is stored in a location which is 4 byte aligned but not 8 byte aligned. In mm/kmemleak.c, scan_block() scans the memory based on 8 byte stride, so it won't detect above pptr, hence reporting the memory leak.

Leer descripción completaMostrar menos

In htab_map_alloc(), we already have

So storing pptr with 8-byte alignment won't cause any problem and can fix kmemleak too.

Detalles técnicos trazas, registros y código del informe original
  unreferenced object 0x606fd7c44ac8 (size 32):
    backtrace (crc 0):
      pcpu_alloc_noprof+0x730/0xeb0
      bpf_map_alloc_percpu+0x69/0xc0
      prealloc_init+0x9d/0x1b0
      htab_map_alloc+0x363/0x510
      map_create+0x215/0x3a0
      __sys_bpf+0x16b/0x3e0
      __x64_sys_bpf+0x18/0x20
      do_syscall_64+0x7b/0x150
      entry_SYSCALL_64_after_hwframe+0x4b/0x53

        htab->elem_size = sizeof(struct htab_elem) +
                          round_up(htab->map.key_size, 8);
        if (percpu)
                htab->elem_size += sizeof(void *);
        else
                htab->elem_size += round_up(htab->map.value_size, 8);

The issue can be reproduced with bpf selftest as well:
  1. Enable CONFIG_DEBUG_KMEMLEAK config
  2. Add a getchar() before skel destroy in test_hash_map() in prog_tests/for_each.c.
     The purpose is to keep map available so kmemleak can be detected.
  3. run './test_progs -t for_each/hash_map &' and a kmemleak should be reported.

CVSS

Probabilidad de explotación (EPSS)

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

Referencias

JSON original (NVD)

Mostrar
{
  "id": "CVE-2025-37807",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Primary",
        "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
      }
    ]
  },
  "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": "824bd0ce6c7c43a9e1e210abf124958e54d88342",
              "lessThan": "7758e308aeda1038aba1944f7302d34161b3effe",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "824bd0ce6c7c43a9e1e210abf124958e54d88342",
              "lessThan": "1f1c29aa1934177349c17e3c32e68ec38a7a56df",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "824bd0ce6c7c43a9e1e210abf124958e54d88342",
              "lessThan": "11ba7ce076e5903e7bdc1fd1498979c331b3c286",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "kernel/bpf/hashtab.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.6"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "4.6",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.12.26",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.14.5",
              "versionType": "semver",
              "lessThanOrEqual": "6.14.*"
            },
            {
              "status": "unaffected",
              "version": "6.15",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "kernel/bpf/hashtab.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2025-05-08T07:15:51.873",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/11ba7ce076e5903e7bdc1fd1498979c331b3c286",
      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/1f1c29aa1934177349c17e3c32e68ec38a7a56df",
      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/7758e308aeda1038aba1944f7302d34161b3effe",
      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "CWE-401"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix kmemleak warning for percpu hashmap\n\nVlad Poenaru reported the following kmemleak issue:\n\n  unreferenced object 0x606fd7c44ac8 (size 32):\n    backtrace (crc 0):\n      pcpu_alloc_noprof+0x730/0xeb0\n      bpf_map_alloc_percpu+0x69/0xc0\n      prealloc_init+0x9d/0x1b0\n      htab_map_alloc+0x363/0x510\n      map_create+0x215/0x3a0\n      __sys_bpf+0x16b/0x3e0\n      __x64_sys_bpf+0x18/0x20\n      do_syscall_64+0x7b/0x150\n      entry_SYSCALL_64_after_hwframe+0x4b/0x53\n\nFurther investigation shows the reason is due to not 8-byte aligned\nstore of percpu pointer in htab_elem_set_ptr():\n  *(void __percpu **)(l->key + key_size) = pptr;\n\nNote that the whole htab_elem alignment is 8 (for x86_64). If the key_size\nis 4, that means pptr is stored in a location which is 4 byte aligned but\nnot 8 byte aligned. In mm/kmemleak.c, scan_block() scans the memory based\non 8 byte stride, so it won't detect above pptr, hence reporting the memory\nleak.\n\nIn htab_map_alloc(), we already have\n\n        htab->elem_size = sizeof(struct htab_elem) +\n                          round_up(htab->map.key_size, 8);\n        if (percpu)\n                htab->elem_size += sizeof(void *);\n        else\n                htab->elem_size += round_up(htab->map.value_size, 8);\n\nSo storing pptr with 8-byte alignment won't cause any problem and can fix\nkmemleak too.\n\nThe issue can be reproduced with bpf selftest as well:\n  1. Enable CONFIG_DEBUG_KMEMLEAK config\n  2. Add a getchar() before skel destroy in test_hash_map() in prog_tests/for_each.c.\n     The purpose is to keep map available so kmemleak can be detected.\n  3. run './test_progs -t for_each/hash_map &' and a kmemleak should be reported."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: bpf: Se corrige la advertencia de kmemleak para el mapa hash de percpu Vlad Poenaru informó el siguiente problema de kmemleak: objeto sin referencia 0x606fd7c44ac8 (tamaño 32): backtrace (crc 0): pcpu_alloc_noprof+0x730/0xeb0 bpf_map_alloc_percpu+0x69/0xc0 prealloc_init+0x9d/0x1b0 htab_map_alloc+0x363/0x510 map_create+0x215/0x3a0 __sys_bpf+0x16b/0x3e0 __x64_sys_bpf+0x18/0x20 do_syscall_64+0x7b/0x150 entry_SYSCALL_64_after_hwframe+0x4b/0x53 Una investigación más profunda muestra que la razón se debe a un almacenamiento no alineado de 8 bytes del puntero por CPU en htab_elem_set_ptr(): *(void __percpu **)(l->key + key_size) = pptr; Tenga en cuenta que la alineación completa de htab_elem es 8 (para x86_64). Si key_size es 4, significa que pptr se almacena en una ubicación que está alineada con 4 bytes pero no con 8 bytes. En mm/kmemleak.c, scan_block() escanea la memoria basándose en un paso de 8 bytes, por lo que no detectará por encima de pptr, por lo que informa la pérdida de memoria. En htab_map_alloc(), ya tenemos htab->elem_size = sizeof(struct htab_elem) + round_up(htab->map.key_size, 8); if (percpu) htab->elem_size += sizeof(void *); else htab->elem_size += round_up(htab->map.value_size, 8); Por lo tanto, almacenar pptr con alineación de 8 bytes no causará ningún problema y también puede solucionar la fuga de kmem. El problema también se puede reproducir con la autoprueba de BPF: 1. Habilite la configuración CONFIG_DEBUG_KMEMLEAK. 2. Añada un getchar() antes de skel destroy en test_hash_map() en prog_tests/for_each.c. El objetivo es mantener el mapa disponible para que se pueda detectar la fuga de kmem. 3. Ejecute './test_progs -t for_each/hash_map &' y se debería informar de una fuga de kmem."
    }
  ],
  "lastModified": "2026-06-17T09:15:28.783",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "505F343C-3DE3-4984-A2E0-52BAFF9CC7CE",
              "versionEndExcluding": "6.12.26"
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "6B25CA7E-4CD0-46DB-B4EF-13A3516071FB",
              "versionEndExcluding": "6.14.5",
              "versionStartIncluding": "6.13"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}