[Bug 219898] New: BLE - Intel AX211 fails to Pair on first attempt but succeeds on second attempt (utilizing software-controlled bluez API via Dbus)

[Bug 219898] New: BLE - Intel AX211 fails to Pair on first attempt but succeeds on second attempt (utilizing software-controlled bluez API via Dbus)

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=219898

            Bug ID: 219898
           Summary: BLE - Intel AX211 fails to Pair on first attempt but
                    succeeds on second attempt (utilizing
                    software-controlled bluez API via Dbus)
           Product: Drivers
           Version: 2.5
          Hardware: Intel
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P3
         Component: Bluetooth
          Assignee: linux-bluetooth@vger.kernel.org
          Reporter: miller.hunterc@gmail.com
        Regression: No

Created attachment 307860
  --> https://bugzilla.kernel.org/attachment.cgi?id=307860&action=edit
btmon trace using pair method via Dbus API

Attempting to Pair with a BLE device fails on the first Pairing attempt, but
succeeds on the second Pairing attempt when utilizing Bluez Dbus API.

When utilizing bluetoothctl directly, this issue does not occur.

Note that this issue does not arise when using Intel AC 9462, but only arises
utilizing Intel AX211.

From the syslogs, it seems new_long_term_key_callback() is never hit during the
first Pair attempt when utilizing dbus API, but is hit when using bluetoothctl
on the first Pair attempt.

I'm unsure where to go from here, but open to suggestions on how to debug this
issue further.

From the btmon log attached, it seems that LE Start Encryption occurs in # 40
(2.293188), followed by success in # 42 (2.294177). However, after the
supervision timeout of 30s, a disconnect is sent # 86 (32.619238).

In the second pair attempt, LE Start Encryption occurs in # 142 (37.979552),
followed by an Encryption Change event in # 143 (38.157560). Following that, a
new long term key event is notified, and pairing succeeds.

Seems as though the Encryption Change event (0x08) only occurs on the second
attempt.

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[Bug 219898] BLE - Intel AX211 fails to Pair on first attempt but succeeds on second attempt (utilizing software-controlled bluez API via Dbus)

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=219898

--- Comment #1 from Hunter M (miller.hunterc@gmail.com) ---
Created attachment 307861
  --> https://bugzilla.kernel.org/attachment.cgi?id=307861&action=edit
Btmon trace using bluetoothctl

Attached is a btmon log file when using bluetoothctl to pair. It looks as
though the LE Start Encryption on # 48 (8.710910) is followed by the Encryption
Change event on # 49 (8.888913). Following that, the new long term key event
occurs and pairing succeeds.

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[Bug 219898] BLE - Intel AX211 fails to Pair on first attempt but succeeds on second attempt (utilizing software-controlled bluez API via Dbus)

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https://bugzilla.kernel.org/show_bug.cgi?id=219898

--- Comment #2 from Hunter M (miller.hunterc@gmail.com) ---
Created attachment 307862
  --> https://bugzilla.kernel.org/attachment.cgi?id=307862&action=edit
Syslog when using Bluez Dbus API

Syslog using Bluez DBus API - shows that new_long_term_key_callback() is not
hit during the first Pair attempt.

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[Bug 219898] BLE - Intel AX211 fails to Pair on first attempt but succeeds on second attempt (utilizing software-controlled bluez API via Dbus)

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https://bugzilla.kernel.org/show_bug.cgi?id=219898

--- Comment #3 from Hunter M (miller.hunterc@gmail.com) ---
Created attachment 307863
  --> https://bugzilla.kernel.org/attachment.cgi?id=307863&action=edit
Syslog when using Bluetoothctl

Syslog attached when using Bluetoothctl. Shows that
new_long_term_key_callback() is hit on first Pair attempt.

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[Bug 219898] BLE - Intel AX211 fails to Pair on first attempt but succeeds on second attempt (utilizing software-controlled bluez API via Dbus)

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=219898

Hunter M (miller.hunterc@gmail.com) changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Kernel Version|                            |6.13.7-arch1-1

--- Comment #4 from Hunter M (miller.hunterc@gmail.com) ---
uname -r
6.13.7-arch1-1

linux-firmware version 20250311
(arch linux version 20250311.b69d4b74-3)

Bluetooth: hci0: Found device firmware: intel/ibt-0040-0041.sfi
Bluetooth: hci0: Firmware Version: 200-48.24

Note that this bug has been reported to Bluez
https://github.com/bluez/bluez/issues/1125.

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[Bug 219898] BLE - Intel AX211 fails to Pair on first attempt but succeeds on second attempt (utilizing software-controlled bluez API via Dbus)

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=219898

--- Comment #5 from Hunter M (miller.hunterc@gmail.com) ---
Created attachment 307872
  --> https://bugzilla.kernel.org/attachment.cgi?id=307872&action=edit
Failed Pair Attempt Air Sniffer snoop

Air sniffer failed pair attempt attached (recommend filter btle.length != 0 in
wireshark to filter out empty PDUs).

From what I can see, Master (computer with AX211) does not send LL_ENC_REQ
after Slave receives Pairing DHKey Check when pairing fails (failed pair
attempt No. 182 and onward).

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[Bug 219898] BLE - Intel AX211 fails to Pair on first attempt but succeeds on second attempt (utilizing software-controlled bluez API via Dbus)

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=219898

--- Comment #6 from Hunter M (miller.hunterc@gmail.com) ---
Created attachment 307873
  --> https://bugzilla.kernel.org/attachment.cgi?id=307873&action=edit
Successful Pair Attempt Air Sniffer log

Air sniffer successful pair attempt (second Pair() attempt via Dbus API).

When pairing succeeds, Master sends LL_ENC_REQ after Slave receives Pairing
DHKey Check (see successful pair attempt No. 67 and No. 70).

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[Bug 219898] BLE - Intel AX211 fails to Pair on first attempt but succeeds on second attempt

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=219898

Hunter M (miller.hunterc@gmail.com) changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|BLE - Intel AX211 fails to  |BLE - Intel AX211 fails to
                   |Pair on first attempt but   |Pair on first attempt but
                   |succeeds on second attempt  |succeeds on second attempt
                   |(utilizing                  |
                   |software-controlled bluez   |
                   |API via Dbus)               |

--- Comment #7 from Hunter M (miller.hunterc@gmail.com) ---
(Apologies for the multiple comments, I should have added this at the start).

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[Bug 219898] BLE - Intel AX211 fails to Pair on first attempt but succeeds on second attempt

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=219898

--- Comment #8 from Hunter M (miller.hunterc@gmail.com) ---
After further testing, issue does occur utilizing bluetoothctl as well. On the
first Pair attempt, org.bluez.Error.AuthenticationCanceled occurs. 

On the second attempt, pairing is successful. 

This issue can be duplicated by removing the /var/lib/bluetooth/<adapter
address>/<remote device address>/ folder and restarting the bluetooth.service
(systemctl restart bluetooth).

Seems that without the cached attributes/info, this issue arises. However, if
the BLE peripheral attributes/info is stored in /var/lib/bluetooth/<adapter
address>/<remote device address>/ folder, the issue does not occur.

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