6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Christiano Amora [ Upstream commit f033482d76a9f18080c7a40c5f9c678bd7adc8f3 ] Bose QC Ultra Headphones (dual-mode, same public address on both transports) occasionally send an SMP Security Request on the BR/EDR SMP fixed channel right after the ACL link is encrypted. The kernel handles it as if it were an LE link: smp_cmd_security_req() has no transport check, smp_ltk_encrypt() looks up an LTK with the ACL connection's dst_type, and hci_find_ltk() matches the peer's LE LTK because the LE public address type is stored as ADDR_LE_DEV_PUBLIC (0), the same value as BDADDR_BREDR. HCI_OP_LE_START_ENC is then issued on the ACL handle, the controller rejects it with Invalid HCI Command Parameters, and hci_cs_le_start_enc() disconnects the link with HCI_ERROR_AUTH_FAILURE. The headphones drop within a second of connecting, before any profile is up; a manual reconnect works. btmon (MediaTek MT7922, kernel 7.0.12): > HCI Event: Encryption Change (0x08) plen 4 Status: Success (0x00) Handle: 50 Address: BC:87:FA:47:73:5E (Bose Corporation) Encryption: Enabled with AES-CCM (0x02) > ACL Data RX: Handle 50 flags 0x02 dlen 6 BR/EDR SMP: Security Request (0x0b) len 1 Authentication requirement: No bonding, No MITM, SC (0x08) < HCI Command: LE Start Encryption (0x08|0x0019) plen 28 Handle: 50 Address: BC:87:FA:47:73:5E (Bose Corporation) > HCI Event: Command Status (0x0f) plen 4 LE Start Encryption (0x08|0x0019) ncmd 1 Status: Invalid HCI Command Parameters (0x12) < HCI Command: Disconnect (0x01|0x0006) plen 3 Handle: 50 Address: BC:87:FA:47:73:5E (Bose Corporation) Reason: Authentication Failure (0x05) SMP over BR/EDR is limited to cross-transport key derivation; the Security Request procedure (Core Specification Vol 3, Part H, Section 2.4.6, PDU in Section 3.6.7) has no BR/EDR counterpart. Reply with Pairing Failed / Command Not Supported on a non-LE link, before the PDU is parsed, and keep the connection. The reply is sent directly rather than through smp_failure(): rejecting a command on the wrong transport is not an authentication failure, and MGMT_EV_AUTH_FAILED would make bluetoothd disconnect the device. Tested on the affected host (kernel 7.0.12, MediaTek MT7922, Bose QC Ultra) with the patched module built out of tree: 7 days and 49 reconnects without a drop, against 2 drops in the 3 days before the patch. Every disconnect in that week had a userspace or remote reason. Fixes: b5ae344d4c0f ("Bluetooth: Add full SMP BR/EDR support") Assisted-by: LLM Signed-off-by: Christiano Amora Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Sasha Levin --- net/bluetooth/smp.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/net/bluetooth/smp.c b/net/bluetooth/smp.c index 1172df9b7004d..51e0545a9e240 100644 --- a/net/bluetooth/smp.c +++ b/net/bluetooth/smp.c @@ -2301,6 +2301,23 @@ static u8 smp_cmd_security_req(struct l2cap_conn *conn, struct sk_buff *skb) bt_dev_dbg(hdev, "conn %p", conn); + /* SMP over BR/EDR only covers cross-transport key derivation; the + * Security Request procedure has no BR/EDR counterpart. Reject it + * here, otherwise smp_ltk_encrypt() finds the peer's LE LTK + * (ADDR_LE_DEV_PUBLIC and BDADDR_BREDR are both 0) and issues + * HCI_OP_LE_START_ENC on the ACL handle, which the controller + * rejects and hci_cs_le_start_enc() turns into a disconnect. Reply + * without smp_failure(): this is not an authentication failure, and + * MGMT_EV_AUTH_FAILED would make bluetoothd drop the device. + */ + if (hcon->type != LE_LINK) { + u8 reason = SMP_CMD_NOTSUPP; + + smp_send_cmd(conn, SMP_CMD_PAIRING_FAIL, sizeof(reason), + &reason); + return 0; + } + if (skb->len < sizeof(*rp)) return SMP_INVALID_PARAMS; -- 2.53.0