CVE-2021-46904 net: hso: fix null-ptr-deref during tty device unregistration

2024-02-2514:03:40

Linux

www.cve.org

linux kernel

vulnerability

null-ptr-deref

tty

unregistration

minor number

get_free_serial_index

obtain_minor

release_minor

AI Score

6.4

Confidence

High

EPSS

Percentile

5.1%

JSON

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

net: hso: fix null-ptr-deref during tty device unregistration

Multiple ttys try to claim the same the minor number causing a double
unregistration of the same device. The first unregistration succeeds
but the next one results in a null-ptr-deref.

The get_free_serial_index() function returns an available minor number
but doesn’t assign it immediately. The assignment is done by the caller
later. But before this assignment, calls to get_free_serial_index()
would return the same minor number.

Fix this by modifying get_free_serial_index to assign the minor number
immediately after one is found to be and rename it to obtain_minor()
to better reflect what it does. Similary, rename set_serial_by_index()
to release_minor() and modify it to free up the minor number of the
given hso_serial. Every obtain_minor() should have corresponding
release_minor() call.

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/net/usb/hso.c"
    ],
    "versions": [
      {
        "version": "72dc1c096c70",
        "lessThan": "a462067d7c8e",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "72dc1c096c70",
        "lessThan": "145c89c441d2",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "72dc1c096c70",
        "lessThan": "caf5ac93b3b5",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "72dc1c096c70",
        "lessThan": "92028d7a31e5",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "72dc1c096c70",
        "lessThan": "4a2933c88399",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "72dc1c096c70",
        "lessThan": "dc195928d7e4",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "72dc1c096c70",
        "lessThan": "388d05f70f1e",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "72dc1c096c70",
        "lessThan": "8a12f8836145",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/net/usb/hso.c"
    ],
    "versions": [
      {
        "version": "2.6.27",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "2.6.27",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "4.4.268",
        "lessThanOrEqual": "4.4.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "4.9.268",
        "lessThanOrEqual": "4.9.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "4.14.232",
        "lessThanOrEqual": "4.14.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "4.19.187",
        "lessThanOrEqual": "4.19.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.4.112",
        "lessThanOrEqual": "5.4.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.10.30",
        "lessThanOrEqual": "5.10.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.11.14",
        "lessThanOrEqual": "5.11.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.12",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]