Public bug reported:
An automated system update migrating the system to the Ubuntu Hardware
Enablement kernel branch (linux-generic-hwe-24.04) introduced a critical
regression that prevents a standard legacy USB Audio Class 1 (UAC1)
interface from initializing.
The device utilizes a Texas Instruments / Burr-Brown USB audio
microcontroller running at Full Speed (12 Mbps) asynchronous stream
parameters. While the hardware remains fully operational on alternative
distributions (e.g., standard Debian-stable based layouts), mobile
platforms, and older kernel revisions, it fails consistently on this HWE
deployment.
The interface mounts correctly at the lowest ALSA layer and appears in
/proc/asound/cards. However, the desktop audio server
(PipeWire/WirePlumber) completely fails to register the stream node
topology. Rapid physical power cycling (disconnecting and re-connecting
the interface within the VBUS gating timeout window) forces a physical
initialization pop, but the underlying data channel remains dead.
The kernel ring buffer reveals a hard memory management fault immediately
following the hardware ring buffer allocation syscall. The crash maps directly
to the CPU's speculative execution mitigation layer (srso_return_thunk),
indicating a regression in how legacy asynchronous USB endpoints are
memory-mapped under current AMD speculative security microcode restrictions.
Steps to Reproduce
Boot a system running the linux-generic-hwe-24.04 kernel branch on
an affected AMD CPU architecture.
Connect a legacy UAC1 Full Speed (12 Mbps) USB audio interface
directly to a native motherboard xHCI USB 3.0 port.
Observe that the device fails to populate in the desktop sound mixer
GUI.
Run dmesg to inspect the speculative execution subsystem fault.
Log Trace (dmesg 20-line stack trace)
Plaintext
[ 368.663789] ? do_syscall_64+0xb6/0xa20
[ 368.663793] ? srso_return_thunk+0x5/0x5f
[ 368.663796] ? do_syscall_64+0xb6/0xa20
[ 368.663799] ? srso_return_thunk+0x5/0x5f
[ 368.663802] ? srso_return_thunk+0x5/0x5f
[ 368.663804] ? arch_exit_to_user_mode_prepare.isra.0+0xd/0xe0
[ 368.663808] ? srso_return_thunk+0x5/0x5f
[ 368.663811] ? do_syscall_64+0xb6/0xa20
[ 368.663814] ? srso_return_thunk+0x5/0x5f
[ 368.663818] entry_SYSCALL_64_after_hwframe+0x76/0x7e
[ 368.663821] RIP: 0033:0x7698f891b215
[ 368.663825] Code: 8b 55 d0 48 89 45 b0 75 a0 44 89 55 9c e8 53 d3 f7 ff 44
8b 55 9c 89 da 4c 89 e6 41 89 c0 bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00
f0 ff ff 77 33 44 89 c7 89 45 9c e8 a8 d3 f7 ff 8b 45 9c
[ 368.663827] RSP: 002b:00007ffedaa06ff0 EFLAGS: 00000293 ORIG_RAX:
0000000000000101
[ 368.663831] RAX: ffffffffffffffda RBX: 0000000000080802 RCX: 00007698f891b215
[ 368.663834] RDX: 0000000000080802 RSI: 00007ffedaa07090 RDI: 00000000ffffff9c
[ 368.663836] RBP: 00007ffedaa07060 R08: 0000000000000000 R09: 0000000000000000
[ 368.663838] R10: 0000000000000000 R11: 0000000000000293 R12: 00007ffedaa07090
[ 368.663840] R13: 0000632aab0a4d08 R14: 00007ffedaa07090 R15: 0000000000000000
[ 368.663846] </TASK>
[ 368.663848] ---[ end trace 0000000000000000 ]---
ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: linux-image-6.17.0-29-generic 6.17.0-29.29~24.04.1
ProcVersionSignature: Ubuntu 6.17.0-29.29~24.04.1-generic 6.17.13
Uname: Linux 6.17.0-29-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.28.1-0ubuntu3.8
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC2: sep2025 2283 F.... wireplumber
/dev/snd/controlC1: sep2025 2283 F.... wireplumber
/dev/snd/seq: sep2025 2280 F.... pipewire
CRDA: N/A
CasperMD5CheckResult: unknown
CurrentDesktop: KDE
Date: Mon May 25 12:02:45 2026
MachineType: Acer Nitro AN515-44
ProcFB: 0 amdgpudrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-6.17.0-29-generic
root=UUID=219443c2-0a61-4bc7-aa9c-6b2a1bde17a5 ro quiet splash
usbcore.autosuspend=-1 pci=noaer iommu=soft 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-6.17.0-29-generic N/A
linux-backports-modules-6.17.0-29-generic N/A
linux-firmware 20240318.git3b128b60-0ubuntu2.27
SourcePackage: linux-hwe-6.17
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 02/04/2021
dmi.bios.release: 1.4
dmi.bios.vendor: Insyde Corp.
dmi.bios.version: V1.04
dmi.board.asset.tag: Type2 - Board Asset Tag
dmi.board.name: Stonic_RNS
dmi.board.vendor: RO
dmi.board.version: V1.04
dmi.chassis.type: 10
dmi.chassis.vendor: Acer
dmi.chassis.version: V1.04
dmi.ec.firmware.release: 1.2
dmi.modalias:
dmi:bvnInsydeCorp.:bvrV1.04:bd02/04/2021:br1.4:efr1.2:svnAcer:pnNitroAN515-44:pvrV1.04:rvnRO:rnStonic_RNS:rvrV1.04:cvnAcer:ct10:cvrV1.04:sku0000000000000000:
dmi.product.family: Nitro 5
dmi.product.name: Nitro AN515-44
dmi.product.sku: 0000000000000000
dmi.product.version: V1.04
dmi.sys.vendor: Acer
** Affects: linux-hwe-6.17 (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug noble
** Description changed:
- Here is the precise text block to paste into the Further Information /
Description field on Launchpad. It contains the core technical data needed for
developers to track the issue.
- Problem Description
-
An automated system update migrating the system to the Ubuntu Hardware
Enablement kernel branch (linux-generic-hwe-24.04) introduced a critical
regression that prevents a standard legacy USB Audio Class 1 (UAC1)
interface from initializing.
The device utilizes a Texas Instruments / Burr-Brown USB audio
microcontroller running at Full Speed (12 Mbps) asynchronous stream
parameters. While the hardware remains fully operational on alternative
distributions (e.g., standard Debian-stable based layouts), mobile
platforms, and older kernel revisions, it fails consistently on this HWE
deployment.
The interface mounts correctly at the lowest ALSA layer and appears in
/proc/asound/cards. However, the desktop audio server
(PipeWire/WirePlumber) completely fails to register the stream node
topology. Rapid physical power cycling (disconnecting and re-connecting
the interface within the VBUS gating timeout window) forces a physical
initialization pop, but the underlying data channel remains dead.
The kernel ring buffer reveals a hard memory management fault immediately
following the hardware ring buffer allocation syscall. The crash maps directly
to the CPU's speculative execution mitigation layer (srso_return_thunk),
indicating a regression in how legacy asynchronous USB endpoints are
memory-mapped under current AMD speculative security microcode restrictions.
Steps to Reproduce
- Boot a system running the linux-generic-hwe-24.04 kernel branch on
+ Boot a system running the linux-generic-hwe-24.04 kernel branch on
an affected AMD CPU architecture.
- Connect a legacy UAC1 Full Speed (12 Mbps) USB audio interface
+ Connect a legacy UAC1 Full Speed (12 Mbps) USB audio interface
directly to a native motherboard xHCI USB 3.0 port.
- Observe that the device fails to populate in the desktop sound mixer
+ Observe that the device fails to populate in the desktop sound mixer
GUI.
- Run dmesg to inspect the speculative execution subsystem fault.
+ Run dmesg to inspect the speculative execution subsystem fault.
Log Trace (dmesg 20-line stack trace)
Plaintext
[ 368.663789] ? do_syscall_64+0xb6/0xa20
[ 368.663793] ? srso_return_thunk+0x5/0x5f
[ 368.663796] ? do_syscall_64+0xb6/0xa20
[ 368.663799] ? srso_return_thunk+0x5/0x5f
[ 368.663802] ? srso_return_thunk+0x5/0x5f
[ 368.663804] ? arch_exit_to_user_mode_prepare.isra.0+0xd/0xe0
[ 368.663808] ? srso_return_thunk+0x5/0x5f
[ 368.663811] ? do_syscall_64+0xb6/0xa20
[ 368.663814] ? srso_return_thunk+0x5/0x5f
[ 368.663818] entry_SYSCALL_64_after_hwframe+0x76/0x7e
[ 368.663821] RIP: 0033:0x7698f891b215
[ 368.663825] Code: 8b 55 d0 48 89 45 b0 75 a0 44 89 55 9c e8 53 d3 f7 ff 44
8b 55 9c 89 da 4c 89 e6 41 89 c0 bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00
f0 ff ff 77 33 44 89 c7 89 45 9c e8 a8 d3 f7 ff 8b 45 9c
[ 368.663827] RSP: 002b:00007ffedaa06ff0 EFLAGS: 00000293 ORIG_RAX:
0000000000000101
[ 368.663831] RAX: ffffffffffffffda RBX: 0000000000080802 RCX:
00007698f891b215
[ 368.663834] RDX: 0000000000080802 RSI: 00007ffedaa07090 RDI:
00000000ffffff9c
[ 368.663836] RBP: 00007ffedaa07060 R08: 0000000000000000 R09:
0000000000000000
[ 368.663838] R10: 0000000000000000 R11: 0000000000000293 R12:
00007ffedaa07090
[ 368.663840] R13: 0000632aab0a4d08 R14: 00007ffedaa07090 R15:
0000000000000000
[ 368.663846] </TASK>
[ 368.663848] ---[ end trace 0000000000000000 ]---
ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: linux-image-6.17.0-29-generic 6.17.0-29.29~24.04.1
ProcVersionSignature: Ubuntu 6.17.0-29.29~24.04.1-generic 6.17.13
Uname: Linux 6.17.0-29-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.28.1-0ubuntu3.8
Architecture: amd64
AudioDevicesInUse:
- USER PID ACCESS COMMAND
- /dev/snd/controlC2: sep2025 2283 F.... wireplumber
- /dev/snd/controlC1: sep2025 2283 F.... wireplumber
- /dev/snd/seq: sep2025 2280 F.... pipewire
+ USER PID ACCESS COMMAND
+ /dev/snd/controlC2: sep2025 2283 F.... wireplumber
+ /dev/snd/controlC1: sep2025 2283 F.... wireplumber
+ /dev/snd/seq: sep2025 2280 F.... pipewire
CRDA: N/A
CasperMD5CheckResult: unknown
CurrentDesktop: KDE
Date: Mon May 25 12:02:45 2026
MachineType: Acer Nitro AN515-44
ProcFB: 0 amdgpudrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-6.17.0-29-generic
root=UUID=219443c2-0a61-4bc7-aa9c-6b2a1bde17a5 ro quiet splash
usbcore.autosuspend=-1 pci=noaer iommu=soft 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-6.17.0-29-generic N/A
- linux-backports-modules-6.17.0-29-generic N/A
- linux-firmware 20240318.git3b128b60-0ubuntu2.27
+ linux-restricted-modules-6.17.0-29-generic N/A
+ linux-backports-modules-6.17.0-29-generic N/A
+ linux-firmware 20240318.git3b128b60-0ubuntu2.27
SourcePackage: linux-hwe-6.17
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 02/04/2021
dmi.bios.release: 1.4
dmi.bios.vendor: Insyde Corp.
dmi.bios.version: V1.04
dmi.board.asset.tag: Type2 - Board Asset Tag
dmi.board.name: Stonic_RNS
dmi.board.vendor: RO
dmi.board.version: V1.04
dmi.chassis.type: 10
dmi.chassis.vendor: Acer
dmi.chassis.version: V1.04
dmi.ec.firmware.release: 1.2
dmi.modalias:
dmi:bvnInsydeCorp.:bvrV1.04:bd02/04/2021:br1.4:efr1.2:svnAcer:pnNitroAN515-44:pvrV1.04:rvnRO:rnStonic_RNS:rvrV1.04:cvnAcer:ct10:cvrV1.04:sku0000000000000000:
dmi.product.family: Nitro 5
dmi.product.name: Nitro AN515-44
dmi.product.sku: 0000000000000000
dmi.product.version: V1.04
dmi.sys.vendor: Acer
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https://bugs.launchpad.net/bugs/2154201
Title:
Kernel regression: linux-generic-hwe-24.04 upgrade causes
srso_return_thunk segmentation fault during USB Audio DAC
initialization
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https://bugs.launchpad.net/ubuntu/+source/linux-hwe-6.17/+bug/2154201/+subscriptions
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