[Bug 218151] New: Bluetooth: Erratic HCI_Command_Status without Inquiry

[Bug 218151] New: Bluetooth: Erratic HCI_Command_Status without Inquiry

[bugzilla-daemon]

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@vger.kernel.org
          Reporter: sy2239101@buaa.edu.cn
        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!

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[Bug 218151] Bluetooth: Erratic HCI_Command_Status without Inquiry

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=218151

Si-Jie Bai (sy2239101@buaa.edu.cn) changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Kernel Version|                            |6.2

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[Bug 218151] Bluetooth: Erratic HCI_Command_Status without Inquiry

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=218151

Si-Jie Bai (sy2239101@buaa.edu.cn) changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |baijiaju1990@gmail.com,
                   |                            |sy2239101@buaa.edu.cn

--- Comment #1 from Si-Jie Bai (sy2239101@buaa.edu.cn) ---
(In reply to Si-Jie Bai from comment #0)
> Created attachment 305410 [details]
> 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!

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[Bug 218151] Bluetooth: Erratic HCI_Command_Status without Inquiry

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=218151

Bagas Sanjaya (bagasdotme@gmail.com) changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bagasdotme@gmail.com

--- Comment #2 from Bagas Sanjaya (bagasdotme@gmail.com) ---
(In reply to Si-Jie Bai from comment #0)
> Created attachment 305410 [details]
> 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!

Can you check latest mainline (currently v6.7-rc1)?

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[Bug 218151] Bluetooth: Erratic HCI_Command_Status without Inquiry

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=218151

Luiz Von Dentz (luiz.dentz@gmail.com) changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |luiz.dentz@gmail.com

--- Comment #3 from Luiz Von Dentz (luiz.dentz@gmail.com) ---
https://patchwork.kernel.org/project/bluetooth/patch/20231120151039.323068-1-luiz.dentz@gmail.com/

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[Bug 218151] Bluetooth: Erratic HCI_Command_Status without Inquiry

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=218151

--- Comment #4 from Si-Jie Bai (sy2239101@buaa.edu.cn) ---
(In reply to Bagas Sanjaya from comment #2)
> (In reply to Si-Jie Bai from comment #0)
> > Created attachment 305410 [details]
> > 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!
> 
> Can you check latest mainline (currently v6.7-rc1)?

Thank you for your valuable input and feedback! I greatly appreciate your
response.

I have confirmed that the bug can be reproduced on the latest mainline and it
generates the same issue.

Comment3 has already provided a patch for this bug:
https://patchwork.kernel.org/project/bluetooth/patch/20231120151039.323068-1-luiz.dentz@gmail.com/

I have confirmed that the bug has been effectively resolved on the latest
mainline with this patch.

I sincerely appreciate your valuable input and solution once again. It has
greatly assisted us in the bug fixing process!

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[Bug 218151] Bluetooth: Erratic HCI_Command_Status without Inquiry

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=218151

--- Comment #5 from Si-Jie Bai (sy2239101@buaa.edu.cn) ---
(In reply to Luiz Von Dentz from comment #3)
> https://patchwork.kernel.org/project/bluetooth/patch/20231120151039.323068-1-
> luiz.dentz@gmail.com/

Thank you for your valuable input and feedback! I greatly appreciate your
response.

I have confirmed that the bug has been effectively resolved on the latest
mainline with this patch.

I sincerely appreciate your valuable input and solution once again. It has
greatly assisted us in the bug fixing process!

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[Bug 218151] Bluetooth: Erratic HCI_Command_Status without Inquiry

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=218151

--- Comment #6 from Luiz Von Dentz (luiz.dentz@gmail.com) ---
(In reply to Si-Jie Bai from comment #5)
> (In reply to Luiz Von Dentz from comment #3)
> >
> https://patchwork.kernel.org/project/bluetooth/patch/20231120151039.323068-1-
> > luiz.dentz@gmail.com/
> 
> Thank you for your valuable input and feedback! I greatly appreciate your
> response.
> 
> I have confirmed that the bug has been effectively resolved on the latest
> mainline with this patch.
> 
> I sincerely appreciate your valuable input and solution once again. It has
> greatly assisted us in the bug fixing process!

Do you mind replying with a Tested-by on the mailing list.

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[Bug 218151] Bluetooth: Erratic HCI_Command_Status without Inquiry

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=218151

Si-Jie Bai (sy2239101@buaa.edu.cn) changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Kernel Version|6.2                         |6.7-rc1

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[Bug 218151] Bluetooth: Erratic HCI_Command_Status without Inquiry

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https://bugzilla.kernel.org/show_bug.cgi?id=218151

--- Comment #7 from Si-Jie Bai (sy2239101@buaa.edu.cn) ---
(In reply to Luiz Von Dentz from comment #6)
> (In reply to Si-Jie Bai from comment #5)
> > (In reply to Luiz Von Dentz from comment #3)
> > >
> >
> https://patchwork.kernel.org/project/bluetooth/patch/20231120151039.323068-1-
> > > luiz.dentz@gmail.com/
> > 
> > Thank you for your valuable input and feedback! I greatly appreciate your
> > response.
> > 
> > I have confirmed that the bug has been effectively resolved on the latest
> > mainline with this patch.
> > 
> > I sincerely appreciate your valuable input and solution once again. It has
> > greatly assisted us in the bug fixing process!
> 
> Do you mind replying with a Tested-by on the mailing list.

Hello Luiz Von Dentz,

I have tested the patch related to bug report 218151 in the Linux kernel
version v6.7-rc1. 

My testing focused on reproducing the steps outlined in the bug report to
evaluate Bluetooth connectivity.

During my tests, I executed the steps to reproduce the bug, and I am pleased to
report that the Bluetooth connection was successful, indicating that the issue
has been resolved in this kernel version.

Based on these results, I can confirm that the patch effectively addresses the
issue in the specified environment.

Tested-by: Si-Jie Bai <sy2239101@buaa.edu.cn>

Best regards,
Si-Jie Bai

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