Public bug reported:
Bluetooth stopped working after upgrading to kernel 6.8.0-139-generic on
Ubuntu 24.04 LTS. It worked correctly on 6.8.0-138-generic.
The btmtk driver crashes with a NULL pointer dereference while loading the
Bluetooth firmware for the MediaTek MT7921 combo chip. The hci0 interface is
created but never completes initialisation: it stays in DOWN INIT state with
BD Address 00:00:00:00:00:00 and all features set to zero. The USB device
disappears from lsusb. WiFi on the same chip (mt7921e) works normally.
Hardware: HP Pavilion Laptop 14-dv2xxx, BIOS F.12 11/02/2023
Chip: MediaTek MT7921 (combo WiFi + Bluetooth)
Firmware: BT_RAM_CODE_MT7961_1_2_hdr.bin.zst present in /lib/firmware/mediatek/
Steps to reproduce:
1. Boot with kernel 6.8.0-139-generic
2. Bluetooth is unavailable in the GNOME settings panel
3. hciconfig -a shows hci0 DOWN INIT RUNNING with a null BD address
Expected: Bluetooth adapter initialises normally, as on 6.8.0-138-generic.
Actual: kernel Oops during btmtk_setup_firmware_79xx, adapter unusable.
Workaround: booting 6.8.0-138-generic restores Bluetooth completely.
Kernel log:
[ 9.292341] Bluetooth: hci0: HW/SW Version: 0x008a008a, Build Time:
20240219111427
[ 9.292355] BUG: kernel NULL pointer dereference, address: 0000000000000219
[ 9.292360] #PF: supervisor read access in kernel mode
[ 9.292362] #PF: error_code(0x0000) - not-present page
[ 9.292370] Oops: 0000 [#1] PREEMPT SMP NOPTI
[ 9.292375] CPU: 8 PID: 141 Comm: kworker/u25:0 Not tainted
6.8.0-139-generic #139-Ubuntu
[ 9.292379] Hardware name: HP HP Pavilion Laptop 14-dv2xxx/89F3, BIOS F.12
11/02/2023
[ 9.292382] Workqueue: hci0 hci_power_on [bluetooth]
[ 9.292450] RIP: 0010:__pm_runtime_resume+0x1b/0x80
[ 9.292489] Call Trace:
[ 9.292491] <TASK>
[ 9.292496] usb_autopm_get_interface+0x1d/0x60
[ 9.292503] btmtk_usb_hci_wmt_sync+0xa9/0x2e0 [btmtk]
[ 9.292508] ? __pfx_btmtk_usb_hci_wmt_sync+0x10/0x10 [btmtk]
[ 9.292512] btmtk_setup_firmware_79xx+0x1c7/0x360 [btmtk]
[ 9.292516] btusb_mtk_setup+0x453/0x610 [btusb]
[ 9.292520] hci_dev_setup_sync+0x6c/0x430 [bluetooth]
[ 9.292524] hci_dev_init_sync+0x3e/0x1c0 [bluetooth]
[ 9.292528] hci_dev_open_sync+0xb1/0x350 [bluetooth]
[ 9.292532] hci_dev_do_open+0x28/0x70 [bluetooth]
[ 9.292536] hci_power_on+0x50/0x210 [bluetooth]
ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: linux-image-6.8.0-138-generic 6.8.0-138.138
ProcVersionSignature: Ubuntu 6.8.0-138.138-generic 6.8.12
Uname: Linux 6.8.0-138-generic x86_64
ApportVersion: 2.28.3-0ubuntu0.1
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: killian 2513 F.... pipewire
killian 2517 F.... wireplumber
/dev/snd/seq: killian 2513 F.... pipewire
CRDA: N/A
CasperMD5CheckResult: unknown
CurrentDesktop: ubuntu:GNOME
Date: Fri Sep 18 08:56:05 2026
InstallationDate: Installed on 2023-06-28 (1178 days ago)
InstallationMedia: Ubuntu 23.04 "Lunar Lobster" - Release amd64 (20230418)
MachineType: HP HP Pavilion Laptop 14-dv2xxx
ProcEnviron:
LANG=fr_FR.UTF-8
PATH=(custom, no user)
SHELL=/bin/bash
TERM=xterm-256color
XDG_RUNTIME_DIR=<set>
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-6.8.0-138-generic
root=UUID=eca5dac5-7a2a-4308-b980-eabb8c1469b3 ro quiet splash
RelatedPackageVersions:
linux-restricted-modules-6.8.0-138-generic N/A
linux-backports-modules-6.8.0-138-generic N/A
linux-firmware 20240318.git3b128b60-0ubuntu2.27
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 11/02/2023
dmi.bios.release: 15.12
dmi.bios.vendor: AMI
dmi.bios.version: F.12
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: 89F3
dmi.board.vendor: HP
dmi.board.version: 14.27
dmi.chassis.type: 10
dmi.chassis.vendor: HP
dmi.chassis.version: Chassis Version
dmi.ec.firmware.release: 14.27
dmi.modalias:
dmi:bvnAMI:bvrF.12:bd11/02/2023:br15.12:efr14.27:svnHP:pnHPPavilionLaptop14-dv2xxx:pvr:rvnHP:rn89F3:rvr14.27:cvnHP:ct10:cvrChassisVersion:sku6Z244EA#ABF:
dmi.product.family: 103C_5335KV HP Pavilion
dmi.product.name: HP Pavilion Laptop 14-dv2xxx
dmi.product.sku: 6Z244EA#ABF
dmi.sys.vendor: HP
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug noble wayland-session
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https://bugs.launchpad.net/bugs/2167679
Title:
btmtk: NULL pointer dereference in usb_autopm_get_interface during
MT7921 firmware setup on 6.8.0-139
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