Public bug reported:
After upgrading to linux-image-6.8.0-139-generic on Ubuntu 24.04 LTS, Bluetooth
stopped
working entirely. The btmtk driver hits a NULL pointer dereference while
setting up the
MT7961 controller firmware, which kills the hci_power_on kworker. As a result
hci0 is
registered (visible in rfkill) but never initialized, and bluetoothctl reports
"No default controller available".
Booting 6.8.0-138-generic makes Bluetooth work again, so this is a regression
introduced
in 6.8.0-139.
Hardware: Acer Aspire A515-57 (Ganymede_ADU), BIOS V1.26 01/23/2024
Bluetooth device: USB 04ca:3802 Lite-On Wireless_Device (MediaTek MT7961, combo
with mt7921e Wi-Fi)
Wi-Fi side (mt7921e) loads fine on both kernels; only Bluetooth is affected.
linux-firmware 20240318.git3b128b60.0ubuntu3.1, BT_RAM_CODE_MT7961_* present in
/lib/firmware/mediatek/
Steps to reproduce:
1. Boot 6.8.0-139-generic
2. bluetoothctl show
Expected: controller is listed.
Actual: "No default controller available", and dmesg shows the Oops below.
Kernel Oops from 6.8.0-139-generic:
[ 3.400181] Bluetooth: hci0: HW/SW Version: 0x008a008a, Build Time:
20240219111427
[ 3.400191] BUG: kernel NULL pointer dereference, address: 0000000000000219
[ 3.400195] #PF: supervisor read access in kernel mode
[ 3.400196] #PF: error_code(0x0000) - not-present page
[ 3.400201] Oops: 0000 [#1] PREEMPT SMP NOPTI
[ 3.400204] CPU: 6 PID: 139 Comm: kworker/u25:0 Not tainted
6.8.0-139-generic #139-Ubuntu
[ 3.400206] Hardware name: Acer Aspire A515-57/Ganymede_ADU, BIOS V1.26
01/23/2024
[ 3.400208] Workqueue: hci0 hci_power_on [bluetooth]
[ 3.400257] RIP: 0010:__pm_runtime_resume+0x1b/0x80
[ 3.400265] RSP: 0018:ffffcced006efb30 EFLAGS: 00010246
[ 3.400267] RAX: ffff89480b5254d0 RBX: 0000000000000050 RCX: 0000000000000000
[ 3.400268] RDX: 0000000000000035 RSI: 0000000000000000 RDI: 0000000000000050
[ 3.400276] CR2: 0000000000000219 CR3: 000000064a63c001 CR4: 0000000000f70ef0
[ 3.400279] Call Trace:
[ 3.400281] <TASK>
[ 3.400284] usb_autopm_get_interface+0x1d/0x60
[ 3.400290] btmtk_usb_hci_wmt_sync+0xa9/0x2e0 [btmtk]
[ 3.400295] btmtk_setup_firmware_79xx+0x1c7/0x360 [btmtk]
[ 3.400298] btusb_mtk_setup+0x453/0x610 [btusb]
[ 3.400302] hci_dev_setup_sync+0x6c/0x430 [bluetooth]
[ 3.400346] hci_dev_init_sync+0x3e/0x1c0 [bluetooth]
[ 3.400381] hci_dev_open_sync+0xb1/0x350 [bluetooth]
[ 3.400414] hci_dev_do_open+0x28/0x70 [bluetooth]
[ 3.400440] hci_power_on+0x50/0x210 [bluetooth]
[ 3.400470] process_one_work+0x181/0x3a0
[ 3.400474] worker_thread+0x18b/0x330
[ 3.400479] kthread+0xef/0x120
[ 3.400482] ret_from_fork+0x44/0x70
[ 3.400487] ret_from_fork_asm+0x1b/0x30
[ 3.400490] </TASK>
Note: this report was filed while running 6.8.0-138-generic (the working
kernel), so the
automatically collected data reflects -138, not the affected -139.
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: bruno 2629 F.... wireplumber
/dev/snd/seq: bruno 2627 F.... pipewire
CRDA: N/A
CasperMD5CheckResult: unknown
CurrentDesktop: ubuntu:GNOME
Date: Sat Sep 5 07:40:39 2026
MachineType: Acer Aspire A515-57
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-6.8.0-138-generic
root=UUID=bddae004-6880-4401-99e0-54b9652f9570 ro quiet splash vt.handoff=7
PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No
PulseAudio daemon running, or not running as session daemon.
RelatedPackageVersions:
linux-restricted-modules-6.8.0-138-generic N/A
linux-backports-modules-6.8.0-138-generic N/A
linux-firmware 20240318.git3b128b60.0ubuntu3.1
SourcePackage: linux
UpgradeStatus: Upgraded to noble on 2025-12-28 (250 days ago)
dmi.bios.date: 01/23/2024
dmi.bios.release: 1.26
dmi.bios.vendor: Insyde Corp.
dmi.bios.version: V1.26
dmi.board.asset.tag: Type2 - Board Asset Tag
dmi.board.name: Ganymede_ADU
dmi.board.vendor: ADL
dmi.board.version: V1.26
dmi.chassis.type: 10
dmi.chassis.vendor: Acer
dmi.chassis.version: V1.26
dmi.ec.firmware.release: 1.26
dmi.modalias:
dmi:bvnInsydeCorp.:bvrV1.26:bd01/23/2024:br1.26:efr1.26:svnAcer:pnAspireA515-57:pvrV1.26:rvnADL:rnGanymede_ADU:rvrV1.26:cvnAcer:ct10:cvrV1.26:sku0000000000000000:
dmi.product.family: Aspire 5
dmi.product.name: Aspire A515-57
dmi.product.sku: 0000000000000000
dmi.product.version: V1.26
dmi.sys.vendor: Acer
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug noble
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https://bugs.launchpad.net/bugs/2166569
Title:
btmtk: NULL pointer dereference in usb_autopm_get_interface during
btmtk_setup_firmware_79xx on 6.8.0-139-generic (MT7961)
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