https://bugzilla.kernel.org/show_bug.cgi?id=218151 Bug ID: 218151 Summary: Bluetooth: Erratic HCI_Command_Status without Inquiry Product: Drivers Version: 2.5 Hardware: Intel OS: Linux Status: NEW Severity: normal Priority: P3 Component: Bluetooth Assignee: linux-bluetooth@xxxxxxxxxxxxxxx Reporter: sy2239101@xxxxxxxxxxx Regression: No Created attachment 305410 --> https://bugzilla.kernel.org/attachment.cgi?id=305410&action=edit wireshark screenshot Our fuzzing tool finds a possible semantic bug in the Bluetooth system in Linux 6.2: According to the core specification v5.4, the HCI_Inquiry command triggers the BR/EDR Controller to enter Inquiry Mode, a process used for discovering nearby BR/EDR Controllers. Furthermore, it is specified that an HCI_Command_Status event should be sent to the Host when the BR/EDR Controller has started the Inquiry process. In our testing, if a related HCI_Command_Status event is sent by the controller without a preceding HCI_Inquiry command from the host, this could lead to a failure in establishing Bluetooth connections. Through our examination and debugging of the Linux 6.2 source code, we have identified the underlying cause of the observed phenomenon: (1.1) When the HCI_Command_Status event related to the HCI_Inquiry command is received, the function hci_cs_inquiry (/net/bluetooth/hci_event.c:2289) is called. (1.2) This leads to the execution of set_bit(HCI_INQUIRY, &hdev->flags); (/net/bluetooth/hci_event.c:2298). (2.1) Upon initiating an ACL connection for the first time, the function hci_acl_create_connection (/net/bluetooth/hci_conn.c:212) is called. (2.2) The result of test_bit(HCI_INQUIRY, &hdev->flags) (/net/bluetooth/hci_conn.c:228) being true causes the connection's state to change to BT_CONNECT2, and the HCI_Inquiry_Cancel command is sent. (3.1) When the HCI_Command_Complete event related to the HCI_Inquiry_Cancel command is received, the function hci_cc_inquiry_cancel (/net/bluetooth/hci_event.c:84) is called. (3.2) The Status field of the HCI_Command_Complete event being 0x0c results in the execution of return rp->status; (/net/bluetooth/hci_event.c:104). (4.1) A timeout triggers hci_conn_timeout (/net/bluetooth/hci_conn.c:638), which in turn calls hci_abort_conn (/net/bluetooth/hci_conn.c:2771). (4.2) This leads to the execution of case BT_CONNECT2: (/net/bluetooth/hci_conn.c:2771), where the HCI_Reject_Connection_Request command is sent. We are not sure whether this is a semantic bug or implementation feature in the Linux kernel. Any feedback would be appreciated, thanks! -- You may reply to this email to add a comment. You are receiving this mail because: You are the assignee for the bug.
