CVE-2024-26903
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.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
| OS | Version | Status | Fixed in |
|---|---|---|---|
| rhel | 9 | fixed | |
| sles | affected | | |
| debian | bookworm | fixed | 6.1.82-1 |
| debian | bullseye | fixed | 5.10.216-1 |
| debian | forky | fixed | 6.7.12-1 |
| debian | sid | fixed | 6.7.12-1 |
| debian | trixie | fixed | 6.7.12-1 |
| linux-kernel | affected | 4.19.311 |
References
- https://access.redhat.com/errata/RHSA-2024:9315
- https://git.kernel.org/stable/c/2535b848fa0f42ddff3e5255cf5e742c9b77bb26
- https://git.kernel.org/stable/c/369f419c097e82407dd429a202cde9a73d3ae29b
- https://git.kernel.org/stable/c/3ead59bafad05f2967ae2438c0528d53244cfde5
- https://git.kernel.org/stable/c/567c0411dc3b424fc7bd1e6109726d7ba32d4f73
- https://git.kernel.org/stable/c/5f369efd9d963c1f711a06c9b8baf9f5ce616d85
- https://git.kernel.org/stable/c/5f9fe302dd3a9bbc50f4888464c1773f45166bfd
- https://git.kernel.org/stable/c/81d7d920a22fd58ef9aedb1bd0a68ee32bd23e96
- https://git.kernel.org/stable/c/8d1753973f598531baaa2c1033cf7f7b5bb004b0
- https://lists.debian.org/debian-lts-announce/2024/06/msg00017.html
- https://lists.debian.org/debian-lts-announce/2024/06/msg00020.html
- https://cert-portal.siemens.com/productcert/html/ssa-265688.html
- https://www.suse.com/security/cve/CVE-2024-26903.html
- https://security-tracker.debian.org/tracker/CVE-2024-26903
CWEs
CWE-476
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.