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CVE-2025-38517

Estado: AnalizadaMedia (5.5)—

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

lib/alloc_tag: do not acquire non-existent lock in alloc_tag_top_users()

alloc_tag_top_users() attempts to lock alloc_tag_cttype->mod_lock even when the alloc_tag_cttype is not allocated because:

In all cases, alloc_tag_cttype is not allocated, and therefore alloc_tag_top_users() should not attempt to acquire the semaphore.

This leads to a crash on memory allocation failure by attempting to acquire a non-existent semaphore:

Before the commit, the issue occurred only when it failed to allocate and initialize alloc_tag_cttype or if a memory allocation fails before alloc_tag_init() is called. After the commit, it can be easily triggered when memory profiling is compiled but disabled at boot.

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To properly determine whether alloc_tag_init() has been called and its data structures initialized, verify that alloc_tag_cttype is a valid pointer before acquiring the semaphore. If the variable is NULL or an error value, it has not been properly initialized. In such a case, just skip and do not attempt to acquire the semaphore.

[harry.yoo@oracle.com: v3]

Detalles técnicos trazas, registros y código del informe original
  1) alloc tagging is disabled because mem profiling is disabled
     (!alloc_tag_cttype)
  2) alloc tagging is enabled, but not yet initialized (!alloc_tag_cttype)
  3) alloc tagging is enabled, but failed initialization
     (!alloc_tag_cttype or IS_ERR(alloc_tag_cttype))

  Oops: general protection fault, probably for non-canonical address 0xdffffc000000001b: 0000 [#3] SMP KASAN NOPTI
  KASAN: null-ptr-deref in range [0x00000000000000d8-0x00000000000000df]
  CPU: 2 UID: 0 PID: 1 Comm: systemd Tainted: G      D             6.16.0-rc2 #1 VOLUNTARY
  Tainted: [D]=DIE
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
  RIP: 0010:down_read_trylock+0xaa/0x3b0
  Code: d0 7c 08 84 d2 0f 85 a0 02 00 00 8b 0d df 31 dd 04 85 c9 75 29 48 b8 00 00 00 00 00 fc ff df 48 8d 6b 68 48 89 ea 48 c1 ea 03 <80> 3c 02 00 0f 85 88 02 00 00 48 3b 5b 68 0f 85 53 01 00 00 65 ff
  RSP: 0000:ffff8881002ce9b8 EFLAGS: 00010016
  RAX: dffffc0000000000 RBX: 0000000000000070 RCX: 0000000000000000
  RDX: 000000000000001b RSI: 000000000000000a RDI: 0000000000000070
  RBP: 00000000000000d8 R08: 0000000000000001 R09: ffffed107dde49d1
  R10: ffff8883eef24e8b R11: ffff8881002cec20 R12: 1ffff11020059d37
  R13: 00000000003fff7b R14: ffff8881002cec20 R15: dffffc0000000000
  FS:  00007f963f21d940(0000) GS:ffff888458ca6000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00007f963f5edf71 CR3: 000000010672c000 CR4: 0000000000350ef0
  Call Trace:
   <TASK>
   codetag_trylock_module_list+0xd/0x20
   alloc_tag_top_users+0x369/0x4b0
   __show_mem+0x1cd/0x6e0
   warn_alloc+0x2b1/0x390
   __alloc_frozen_pages_noprof+0x12b9/0x21a0
   alloc_pages_mpol+0x135/0x3e0
   alloc_slab_page+0x82/0xe0
   new_slab+0x212/0x240
   ___slab_alloc+0x82a/0xe00
   </TASK>

As David Wang points out, this issue became easier to trigger after commit
780138b12381 ("alloc_tag: check mem_profiling_support in alloc_tag_init").

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-2025-38517",
  "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": "1438d349d16b78d88f9e978a4a5496f078c8191b",
              "lessThan": "febc0b5dbabda414565bdfaaaa59d26f787d5fe7",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "1438d349d16b78d88f9e978a4a5496f078c8191b",
              "lessThan": "22bf79c0c2301b6e15a688220284b147774d277e",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "1438d349d16b78d88f9e978a4a5496f078c8191b",
              "lessThan": "99af22cd34688cc0d535a1919e0bea4cbc6c1ea1",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "lib/alloc_tag.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.10"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "6.10",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.12.39",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.15.7",
              "versionType": "semver",
              "lessThanOrEqual": "6.15.*"
            },
            {
              "status": "unaffected",
              "version": "6.16",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "lib/alloc_tag.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2025-08-16T11:15:44.897",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/22bf79c0c2301b6e15a688220284b147774d277e",
      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/99af22cd34688cc0d535a1919e0bea4cbc6c1ea1",
      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/febc0b5dbabda414565bdfaaaa59d26f787d5fe7",
      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "CWE-476"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nlib/alloc_tag: do not acquire non-existent lock in alloc_tag_top_users()\n\nalloc_tag_top_users() attempts to lock alloc_tag_cttype->mod_lock even\nwhen the alloc_tag_cttype is not allocated because:\n\n  1) alloc tagging is disabled because mem profiling is disabled\n     (!alloc_tag_cttype)\n  2) alloc tagging is enabled, but not yet initialized (!alloc_tag_cttype)\n  3) alloc tagging is enabled, but failed initialization\n     (!alloc_tag_cttype or IS_ERR(alloc_tag_cttype))\n\nIn all cases, alloc_tag_cttype is not allocated, and therefore\nalloc_tag_top_users() should not attempt to acquire the semaphore.\n\nThis leads to a crash on memory allocation failure by attempting to\nacquire a non-existent semaphore:\n\n  Oops: general protection fault, probably for non-canonical address 0xdffffc000000001b: 0000 [#3] SMP KASAN NOPTI\n  KASAN: null-ptr-deref in range [0x00000000000000d8-0x00000000000000df]\n  CPU: 2 UID: 0 PID: 1 Comm: systemd Tainted: G      D             6.16.0-rc2 #1 VOLUNTARY\n  Tainted: [D]=DIE\n  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014\n  RIP: 0010:down_read_trylock+0xaa/0x3b0\n  Code: d0 7c 08 84 d2 0f 85 a0 02 00 00 8b 0d df 31 dd 04 85 c9 75 29 48 b8 00 00 00 00 00 fc ff df 48 8d 6b 68 48 89 ea 48 c1 ea 03 <80> 3c 02 00 0f 85 88 02 00 00 48 3b 5b 68 0f 85 53 01 00 00 65 ff\n  RSP: 0000:ffff8881002ce9b8 EFLAGS: 00010016\n  RAX: dffffc0000000000 RBX: 0000000000000070 RCX: 0000000000000000\n  RDX: 000000000000001b RSI: 000000000000000a RDI: 0000000000000070\n  RBP: 00000000000000d8 R08: 0000000000000001 R09: ffffed107dde49d1\n  R10: ffff8883eef24e8b R11: ffff8881002cec20 R12: 1ffff11020059d37\n  R13: 00000000003fff7b R14: ffff8881002cec20 R15: dffffc0000000000\n  FS:  00007f963f21d940(0000) GS:ffff888458ca6000(0000) knlGS:0000000000000000\n  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n  CR2: 00007f963f5edf71 CR3: 000000010672c000 CR4: 0000000000350ef0\n  Call Trace:\n   <TASK>\n   codetag_trylock_module_list+0xd/0x20\n   alloc_tag_top_users+0x369/0x4b0\n   __show_mem+0x1cd/0x6e0\n   warn_alloc+0x2b1/0x390\n   __alloc_frozen_pages_noprof+0x12b9/0x21a0\n   alloc_pages_mpol+0x135/0x3e0\n   alloc_slab_page+0x82/0xe0\n   new_slab+0x212/0x240\n   ___slab_alloc+0x82a/0xe00\n   </TASK>\n\nAs David Wang points out, this issue became easier to trigger after commit\n780138b12381 (\"alloc_tag: check mem_profiling_support in alloc_tag_init\").\n\nBefore the commit, the issue occurred only when it failed to allocate and\ninitialize alloc_tag_cttype or if a memory allocation fails before\nalloc_tag_init() is called.  After the commit, it can be easily triggered\nwhen memory profiling is compiled but disabled at boot.\n\nTo properly determine whether alloc_tag_init() has been called and its\ndata structures initialized, verify that alloc_tag_cttype is a valid\npointer before acquiring the semaphore.  If the variable is NULL or an\nerror value, it has not been properly initialized.  In such a case, just\nskip and do not attempt to acquire the semaphore.\n\n[harry.yoo@oracle.com: v3]"
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: lib/alloc_tag: no adquiere un bloqueo inexistente en alloc_tag_top_users() alloc_tag_top_users() intenta bloquear alloc_tag_cttype-&gt;mod_lock incluso cuando alloc_tag_cttype no está asignado porque: 1) el etiquetado de asignación está deshabilitado porque el perfil de memoria está deshabilitado (!alloc_tag_cttype) 2) el etiquetado de asignación está habilitado, pero aún no se ha inicializado (!alloc_tag_cttype) 3) el etiquetado de asignación está habilitado, pero falló la inicialización (!alloc_tag_cttype o IS_ERR(alloc_tag_cttype)) En todos los casos, alloc_tag_cttype no está asignado y, por lo tanto, alloc_tag_top_users() no debe intentar adquirir el semáforo. Esto genera un bloqueo por un error de asignación de memoria al intentar adquirir un semáforo inexistente: Oops: error de protección general, probablemente para una dirección no canónica 0xdffffc000000001b: 0000 [#3] SMP KASAN NOPTI KASAN: null-ptr-deref en el rango [0x0000000000000d8-0x00000000000000df] CPU: 2 UID: 0 PID: 1 Comm: systemd Tainted: GD 6.16.0-rc2 #1 VOLUNTARY Tainted: [D]=DIE Nombre del hardware: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 RIP: 0010:down_read_trylock+0xaa/0x3b0 Código: d0 7c 08 84 d2 0f 85 a0 02 00 00 8b 0d df 31 dd 04 85 c9 75 29 48 b8 00 00 00 00 00 fc ff df 48 8d 6b 68 48 89 ea 48 c1 ea 03 &lt;80&gt; 3c 02 00 0f 85 88 02 00 00 48 3b 5b 68 0f 85 53 01 00 00 65 ff RSP: 0000:ffff8881002ce9b8 EFLAGS: 00010016 RAX: dffffc0000000000 RBX: 0000000000000070 RCX: 0000000000000000 RDX: 0000000000000001b RSI: 000000000000000a RDI: 0000000000000070 RBP: 00000000000000d8 R08: 0000000000000001 R09: ffffed107dde49d1 R10: ffff8883eef24e8b R11: ffff8881002cec20 R12: 1ffff11020059d37 R13: 00000000003fff7b R14: ffff8881002cec20 R15: dffffc0000000000 FS: 00007f963f21d940(0000) GS:ffff888458ca6000(0000) knlGS:000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f963f5edf71 CR3: 000000010672c000 CR4: 0000000000350ef0 Rastreo de llamadas:  codetag_trylock_module_list+0xd/0x20 Como señala David Wang, este problema se volvió más fácil de activar después de el commit 780138b12381 (\"alloc_tag: verificar mem_profiling_support en alloc_tag_init\"). Antes de el commit, el problema solo ocurría cuando no se asignaba ni inicializaba alloc_tag_cttype o si fallaba la asignación de memoria antes de llamar a alloc_tag_init(). Después de el commit, se puede activar fácilmente cuando el perfilado de memoria se compila, pero se deshabilita al arrancar. Para determinar correctamente si se ha llamado a alloc_tag_init() y si se han inicializado sus estructuras de datos, verifique que alloc_tag_cttype sea un puntero válido antes de adquirir el semáforo. Si la variable es NULL o un valor de error, no se ha inicializado correctamente. En tal caso, simplemente omita este paso y no intente adquirir el semáforo. [harry.yoo@oracle.com: v3]"
    }
  ],
  "lastModified": "2026-06-17T09:17:01.753",
  "configurations": [
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      "nodes": [
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