GHSA-H78P-V7HC-728F

Vulnerability from github – Published: 2024-02-28 09:30 – Updated: 2024-12-31 18:30
VLAI?
Details

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().

Severity ?
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Show details on source website
To clipboard 

{
  "affected": [],
  "aliases": [
    "CVE-2021-46986"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-416"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-02-28T09:15:37Z",
    "severity": "MODERATE"
  },
  "details": "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().",
  "id": "GHSA-h78p-v7hc-728f",
  "modified": "2024-12-31T18:30:50Z",
  "published": "2024-02-28T09:30:37Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-46986"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1ea775021282d90e1d08d696b7ab54aa75d688e5"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b4b8e9601d7ee8806d2687f081a42485d27674a1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/bb9c74a5bd1462499fe5ccb1e3c5ac40dcfa9139"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/bc0cdd72493236fb72b390ad38ce581e353c143c"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Detection rules are retrieved from Rulezet.