ghsa-w69g-9g23-pfwc
Vulnerability from github
Published
2024-04-17 12:32
Modified
2024-06-27 12:30
Severity ?
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Details

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

Bluetooth: rfcomm: Fix null-ptr-deref in rfcomm_check_security

During our fuzz testing of the connection and disconnection process at the RFCOMM layer, we discovered this bug. By comparing the packets from a normal connection and disconnection process with the testcase that triggered a KASAN report. We analyzed the cause of this bug as follows:

  1. In the packets captured during a normal connection, the host sends a Read Encryption Key Size type of HCI_CMD packet (Command Opcode: 0x1408) to the controller to inquire the length of encryption key.After receiving this packet, the controller immediately replies with a Command Completepacket (Event Code: 0x0e) to return the Encryption Key Size.

  2. In our fuzz test case, the timing of the controller's response to this packet was delayed to an unexpected point: after the RFCOMM and L2CAP layers had disconnected but before the HCI layer had disconnected.

  3. After receiving the Encryption Key Size Response at the time described in point 2, the host still called the rfcomm_check_security function. However, by this time struct l2cap_conn *conn = l2cap_pi(sk)->chan->conn; had already been released, and when the function executed return hci_conn_security(conn->hcon, d->sec_level, auth_type, d->out);, specifically when accessing conn->hcon, a null-ptr-deref error occurred.

To fix this bug, check if sk->sk_state is BT_CLOSED before calling rfcomm_recv_frame in rfcomm_process_rx.

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{
  "affected": [],
  "aliases": [
    "CVE-2024-26903"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-476"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-04-17T11:15:11Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: rfcomm: Fix null-ptr-deref in rfcomm_check_security\n\nDuring our fuzz testing of the connection and disconnection process at the\nRFCOMM layer, we discovered this bug. By comparing the packets from a\nnormal connection and disconnection process with the testcase that\ntriggered a KASAN report. We analyzed the cause of this bug as follows:\n\n1. In the packets captured during a normal connection, the host sends a\n`Read Encryption Key Size` type of `HCI_CMD` packet\n(Command Opcode: 0x1408) to the controller to inquire the length of\nencryption key.After receiving this packet, the controller immediately\nreplies with a Command Completepacket (Event Code: 0x0e) to return the\nEncryption Key Size.\n\n2. In our fuzz test case, the timing of the controller\u0027s response to this\npacket was delayed to an unexpected point: after the RFCOMM and L2CAP\nlayers had disconnected but before the HCI layer had disconnected.\n\n3. After receiving the Encryption Key Size Response at the time described\nin point 2, the host still called the rfcomm_check_security function.\nHowever, by this time `struct l2cap_conn *conn = l2cap_pi(sk)-\u003echan-\u003econn;`\nhad already been released, and when the function executed\n`return hci_conn_security(conn-\u003ehcon, d-\u003esec_level, auth_type, d-\u003eout);`,\nspecifically when accessing `conn-\u003ehcon`, a null-ptr-deref error occurred.\n\nTo fix this bug, check if `sk-\u003esk_state` is BT_CLOSED before calling\nrfcomm_recv_frame in rfcomm_process_rx.",
  "id": "GHSA-w69g-9g23-pfwc",
  "modified": "2024-06-27T12:30:45Z",
  "published": "2024-04-17T12:32:05Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-26903"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2535b848fa0f42ddff3e5255cf5e742c9b77bb26"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/369f419c097e82407dd429a202cde9a73d3ae29b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3ead59bafad05f2967ae2438c0528d53244cfde5"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/567c0411dc3b424fc7bd1e6109726d7ba32d4f73"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5f369efd9d963c1f711a06c9b8baf9f5ce616d85"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5f9fe302dd3a9bbc50f4888464c1773f45166bfd"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/81d7d920a22fd58ef9aedb1bd0a68ee32bd23e96"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8d1753973f598531baaa2c1033cf7f7b5bb004b0"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2024/06/msg00017.html"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2024/06/msg00020.html"
    }
  ],
  "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"
    }
  ]
}


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