Attacker Value
Unknown
(0 users assessed)
Exploitability
Unknown
(0 users assessed)
User Interaction
None
Privileges Required
Low
Attack Vector
Local
0

CVE-2024-26903

Disclosure Date: April 17, 2024
Add MITRE ATT&CK tactics and techniques that apply to this CVE.

Description

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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CVSS V3 Severity and Metrics
Base Score:
5.5 Medium
Impact Score:
3.6
Exploitability Score:
1.8
Vector:
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector (AV):
Local
Attack Complexity (AC):
Low
Privileges Required (PR):
Low
User Interaction (UI):
None
Scope (S):
Unchanged
Confidentiality (C):
None
Integrity (I):
None
Availability (A):
High

General Information

Vendors

  • linux

Products

  • linux kernel
Technical Analysis