FKIE_CVE-2021-46986

Vulnerability from fkie_nvd - Published: 2024-02-28 09:15 - Updated: 2024-12-31 16:14
Severity ?
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: usb: dwc3: gadget: Free gadget structure only after freeing endpoints As part of commit e81a7018d93a ("usb: dwc3: allocate gadget structure dynamically") the dwc3_gadget_release() was added which will free the dwc->gadget structure upon the device's removal when usb_del_gadget_udc() is called in dwc3_gadget_exit(). However, simply freeing the gadget results a dangling pointer situation: the endpoints created in dwc3_gadget_init_endpoints() have their dep->endpoint.ep_list members chained off the list_head anchored at dwc->gadget->ep_list. Thus when dwc->gadget is freed, the first dwc3_ep in the list now has a dangling prev pointer and likewise for the next pointer of the dwc3_ep at the tail of the list. The dwc3_gadget_free_endpoints() that follows will result in a use-after-free when it calls list_del(). This was caught by enabling KASAN and performing a driver unbind. The recent commit 568262bf5492 ("usb: dwc3: core: Add shutdown callback for dwc3") also exposes this as a panic during shutdown. There are a few possibilities to fix this. One could be to perform a list_del() of the gadget->ep_list itself which removes it from the rest of the dwc3_ep chain. Another approach is what this patch does, by splitting up the usb_del_gadget_udc() call into its separate "del" and "put" components. This allows dwc3_gadget_free_endpoints() to be called before the gadget is finally freed with usb_put_gadget().
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/1ea775021282d90e1d08d696b7ab54aa75d688e5Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/b4b8e9601d7ee8806d2687f081a42485d27674a1Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/bb9c74a5bd1462499fe5ccb1e3c5ac40dcfa9139Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/bc0cdd72493236fb72b390ad38ce581e353c143cPatch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/1ea775021282d90e1d08d696b7ab54aa75d688e5Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/b4b8e9601d7ee8806d2687f081a42485d27674a1Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/bb9c74a5bd1462499fe5ccb1e3c5ac40dcfa9139Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/bc0cdd72493236fb72b390ad38ce581e353c143cPatch
Impacted products
Vendor Product Version
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel 5.13
To clipboard 

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  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nusb: dwc3: gadget: Free gadget structure only after freeing endpoints\n\nAs part of commit e81a7018d93a (\"usb: dwc3: allocate gadget structure\ndynamically\") the dwc3_gadget_release() was added which will free\nthe dwc-\u003egadget structure upon the device\u0027s removal when\nusb_del_gadget_udc() is called in dwc3_gadget_exit().\n\nHowever, simply freeing the gadget results a dangling pointer\nsituation: the endpoints created in dwc3_gadget_init_endpoints()\nhave their dep-\u003eendpoint.ep_list members chained off the list_head\nanchored at dwc-\u003egadget-\u003eep_list.  Thus when dwc-\u003egadget is freed,\nthe first dwc3_ep in the list now has a dangling prev pointer and\nlikewise for the next pointer of the dwc3_ep at the tail of the list.\nThe dwc3_gadget_free_endpoints() that follows will result in a\nuse-after-free when it calls list_del().\n\nThis was caught by enabling KASAN and performing a driver unbind.\nThe recent commit 568262bf5492 (\"usb: dwc3: core: Add shutdown\ncallback for dwc3\") also exposes this as a panic during shutdown.\n\nThere are a few possibilities to fix this.  One could be to perform\na list_del() of the gadget-\u003eep_list itself which removes it from\nthe rest of the dwc3_ep chain.\n\nAnother approach is what this patch does, by splitting up the\nusb_del_gadget_udc() call into its separate \"del\" and \"put\"\ncomponents.  This allows dwc3_gadget_free_endpoints() to be\ncalled before the gadget is finally freed with usb_put_gadget()."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se resolvi\u00f3 la siguiente vulnerabilidad: usb: dwc3: gadget: estructura de gadget libre solo despu\u00e9s de liberar los puntos finales. Como parte de el commit e81a7018d93a (\"usb: dwc3: asignar estructura de gadget din\u00e1micamente\"), se agreg\u00f3 dwc3_gadget_release() que libere la estructura dwc-\u0026gt;gadget al retirar el dispositivo cuando se llama a usb_del_gadget_udc() en dwc3_gadget_exit(). Sin embargo, simplemente liberar el gadget da como resultado una situaci\u00f3n de puntero colgante: los puntos finales creados en dwc3_gadget_init_endpoints() tienen sus miembros dep-\u0026gt;endpoint.ep_list encadenados fuera del list_head anclado en dwc-\u0026gt;gadget-\u0026gt;ep_list. Por lo tanto, cuando se libera dwc-\u0026gt;gadget, el primer dwc3_ep de la lista ahora tiene un puntero anterior colgante y lo mismo ocurre con el siguiente puntero de dwc3_ep al final de la lista. El dwc3_gadget_free_endpoints() que sigue dar\u00e1 como resultado un use-after-free cuando llame a list_del(). Esto se detect\u00f3 habilitando KASAN y realizando una desvinculaci\u00f3n del controlador. La reciente confirmaci\u00f3n 568262bf5492 (\"usb: dwc3: core: Add Shutdown Callback for dwc3\") tambi\u00e9n expone esto como un p\u00e1nico durante el apagado. Hay algunas posibilidades para solucionar este problema. Una podr\u00eda ser realizar un list_del() del propio gadget-\u0026gt;ep_list que lo elimine del resto de la cadena dwc3_ep. Otro enfoque es lo que hace este parche, al dividir la llamada usb_del_gadget_udc() en sus componentes separados \"del\" y \"put\". Esto permite llamar a dwc3_gadget_free_endpoints() antes de que el gadget se libere finalmente con usb_put_gadget()."
    }
  ],
  "id": "CVE-2021-46986",
  "lastModified": "2024-12-31T16:14:55.390",
  "metrics": {
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        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 5.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
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        "source": "nvd@nist.gov",
        "type": "Primary"
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  "published": "2024-02-28T09:15:37.540",
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  "vulnStatus": "Analyzed",
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      "source": "nvd@nist.gov",
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}


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