FKIE_CVE-2025-38632

Vulnerability from fkie_nvd - Published: 2025-08-22 16:15 - Updated: 2025-11-26 17:11
Severity ?
4.7 (Medium) - CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: pinmux: fix race causing mux_owner NULL with active mux_usecount commit 5a3e85c3c397 ("pinmux: Use sequential access to access desc->pinmux data") tried to address the issue when two client of the same gpio calls pinctrl_select_state() for the same functionality, was resulting in NULL pointer issue while accessing desc->mux_owner. However, issue was not completely fixed due to the way it was handled and it can still result in the same NULL pointer. The issue occurs due to the following interleaving: cpu0 (process A) cpu1 (process B) pin_request() { pin_free() { mutex_lock() desc->mux_usecount--; //becomes 0 .. mutex_unlock() mutex_lock(desc->mux) desc->mux_usecount++; // becomes 1 desc->mux_owner = owner; mutex_unlock(desc->mux) mutex_lock(desc->mux) desc->mux_owner = NULL; mutex_unlock(desc->mux) This sequence leads to a state where the pin appears to be in use (`mux_usecount == 1`) but has no owner (`mux_owner == NULL`), which can cause NULL pointer on next pin_request on the same pin. Ensure that updates to mux_usecount and mux_owner are performed atomically under the same lock. Only clear mux_owner when mux_usecount reaches zero and no new owner has been assigned.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0b075c011032f88d1cfde3b45d6dcf08b44140ebPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/22b585cbd67d14df3b91529d1b990661c300faa9Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/9b2a3e7189028aa7c4d53a84364f2ea9fb209787Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/9ea3f6b9a67be3476e331ce51cac316c2614a564Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/b7bd6e3971eb7f0e34d2fdce1b18b08094e0c804Patch
Impacted products
Vendor Product Version
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
To clipboard 

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  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\npinmux: fix race causing mux_owner NULL with active mux_usecount\n\ncommit 5a3e85c3c397 (\"pinmux: Use sequential access to access\ndesc-\u003epinmux data\") tried to address the issue when two client of the\nsame gpio calls pinctrl_select_state() for the same functionality, was\nresulting in NULL pointer issue while accessing desc-\u003emux_owner.\nHowever, issue was not completely fixed due to the way it was handled\nand it can still result in the same NULL pointer.\n\nThe issue occurs due to the following interleaving:\n\n     cpu0 (process A)                   cpu1 (process B)\n\n      pin_request() {                   pin_free() {\n\n                                         mutex_lock()\n                                         desc-\u003emux_usecount--; //becomes 0\n                                         ..\n                                         mutex_unlock()\n\n  mutex_lock(desc-\u003emux)\n  desc-\u003emux_usecount++; // becomes 1\n  desc-\u003emux_owner = owner;\n  mutex_unlock(desc-\u003emux)\n\n                                         mutex_lock(desc-\u003emux)\n                                         desc-\u003emux_owner = NULL;\n                                         mutex_unlock(desc-\u003emux)\n\nThis sequence leads to a state where the pin appears to be in use\n(`mux_usecount == 1`) but has no owner (`mux_owner == NULL`), which can\ncause NULL pointer on next pin_request on the same pin.\n\nEnsure that updates to mux_usecount and mux_owner are performed\natomically under the same lock. Only clear mux_owner when mux_usecount\nreaches zero and no new owner has been assigned."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: pinmux: correcci\u00f3n de la carrera que causaba que mux_owner fuera nulo con el commit 5a3e85c3c397 de mux_usecount activa (\"pinmux: Usar acceso secuencial para acceder a los datos de desc-\u0026gt;pinmux\"). Se intent\u00f3 solucionar el problema cuando dos clientes del mismo GPIO llamaban a pinctrl_select_state() para la misma funcionalidad, lo que provocaba un problema de puntero nulo al acceder a desc-\u0026gt;mux_owner. Sin embargo, el problema no se solucion\u00f3 por completo debido a la forma en que se gestion\u00f3 y a\u00fan puede resultar en el mismo puntero nulo. El problema se produce debido a la siguiente intercalaci\u00f3n: cpu0 (proceso A) cpu1 (proceso B) pin_request() { pin_free() { mutex_lock() desc-\u0026gt;mux_usecount--; //se convierte en 0 .. mutex_unlock() mutex_lock(desc-\u0026gt;mux) desc-\u0026gt;mux_usecount++; // se convierte en 1 desc-\u0026gt;mux_owner = owner; mutex_unlock(desc-\u0026gt;mux) mutex_lock(desc-\u0026gt;mux) desc-\u0026gt;mux_owner = NULL; mutex_unlock(desc-\u0026gt;mux) Esta secuencia lleva a un estado donde el pin parece estar en uso (`mux_usecount == 1`) pero no tiene propietario (`mux_owner == NULL`), lo que puede generar un puntero nulo en la siguiente solicitud de pin en el mismo pin. Aseg\u00farese de que las actualizaciones de mux_usecount y mux_owner se realicen autom\u00e1ticamente bajo el mismo bloqueo. Solo borre mux_owner cuando mux_usecount llegue a cero y no se haya asignado un nuevo propietario."
    }
  ],
  "id": "CVE-2025-38632",
  "lastModified": "2025-11-26T17:11:43.133",
  "metrics": {
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          "attackComplexity": "HIGH",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 4.7,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
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        "impactScore": 3.6,
        "source": "nvd@nist.gov",
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  "published": "2025-08-22T16:15:37.033",
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      "source": "nvd@nist.gov",
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}


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