Kubuntu 23.10: Kernel Bug Invoking Undefined Behavior on Boot

[Aeryn Scheffert]

Apologies if what this post will entail is not the correct way to report a bug. This is my first time reporting one for a linux distro, and I'm more or less doing so based on information I was told while investigating a separate issue related to my audio devices.

On boot, along with the error I was looking for, I noticed a number of UBSan errors pop up. I asked about them in a linux-related discord server and their first question was whether the kernel was compiled with Clang. Now, because I never mess with the kernel, I told them I wasn't sure. That was when they told me that it's a kernel bug that invoked undefined behavior and left my kernel in an erroneous state. Here are the errors in question:

[ 5.036942] UBSAN: array-index-out-of-bounds in /build/linux-SXblTa/linux-6.5.0/drivers/gpu/drm/amd/amdgpu/../pm/powerplay/hwmgr/smu7_hwmgr.c:3669:4
[ 5.036951] index 2 is out of range for type 'ATOM_Tonga_MCLK_Dependency_Record [1]'
[ 5.041843] UBSAN: array-index-out-of-bounds in /build/linux-SXblTa/linux-6.5.0/drivers/gpu/drm/amd/amdgpu/../pm/powerplay/hwmgr/smu7_hwmgr.c:3676:4
[ 5.041852] index 7 is out of range for type 'ATOM_Polaris_SCLK_Dependency_Record [1]'

Because I'm not 100% sure what all goes into a bug report like this, I will be providing the output of lsb_release -rd, hyfetch, and creating a list of my system's specs in hopes that it will help provide some sort of clarity.

lsb_release -rd Output:
-----------------------
No LSB modules are available.
Description: Ubuntu 23.10
Release: 23.10

Hyfetch Output:
---------------
OS: Kubuntu 23.10 x86_64
Kernel: 6.5.0-14-generic
Uptime: 28 mins
Packages: 3 (pipx), 4178 (dpkg), 43 (flatpak), 24 (snap)
Shell: fish 3.6.1 (yes I know it's deprecated but I prefer it over other shells)
Resolution: 1920x1080, 1920x1080
DE: Plasma 5.27.8 [KF5 5.110.0] [Qt 5.15.10] (x11)
WM: KWin

System Specs:
-------------
CPU: AMD Ryzen 5 2600x
GPU: Sapphire NITRO+ Radeon RX 570
MOBO: ASUS PRIME B450M-A II
RAM: TEAMGROUP TUFF Gaming 2x8 GB at 2400 MHz
PSU: Corsair RM850x (850W PSU)
SSD: Western Digital Blue 1 TB SSD

I'll be honest and say I'm not even sure if my system specs are required for a bug report like this, but just in case I figured I'd provide them anyway, as maybe it's a hardware-specific thing, or something specific to my system entirely. I'm not sure though. I also went ahead and included an attachment of the photo I took of the error itself, maybe it'll help in some way. I'm also unsure if there's a package related to this bug, or what that package would be. Sorry.

As for the last two things stated in the guidelines for reporting a bug, what I expected to happen was to see the error about my USB device along with some of the general jargon that pops up on boot that I typically don't have to worry about. Instead what happened is that based on what someone else told me, I found a bug in my kernel, although I'm not knowledgeable enough to know if it's a serious bug, or something that's really not that big of a deal. I'll leave that one up to you guys

[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. It seems that your bug report is not filed about a specific source package though, rather it is just filed against Ubuntu in general. It is important that bug reports be filed about source packages so that people interested in the package can find the bugs about it. You can find some hints about determining what package your bug might be about at https://wiki.ubuntu.com/Bugs/FindRightPackage. You might also ask for help in the #ubuntu-bugs irc channel on Libera.chat.

To change the source package that this bug is filed about visit https://bugs.launchpad.net/ubuntu/+bug/2045992/+editstatus and add the package name in the text box next to the word Package.

[This is an automated message. I apologize if it reached you inappropriately; please just reply to this message indicating so.]

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[JohnDoe_71Rus (johndoe99)]

Lubuntu 22.04 with hwe

linux-generic-hwe-22.04 (6.5.0.14.14~22.04.7)

this is not affected with 6.2.0.39.40~22.04.16

hardware

GA 970A-DS3P (bios version FD)
video Baffin [Radeon RX 550 640SP / RX 560/560X] Mesa 23.2.1-1ubuntu3.1~22.04.1

[JohnDoe_71Rus (johndoe99)]

kernel log

[Cole Risch (metal-flow)]

This affects me too... I run a different GPU, so I will post my DMESG here as well:

   13.349657] ================================================================================
[ 13.349666] UBSAN: array-index-out-of-bounds in /build/linux-SXblTa/linux-6.5.0/drivers/gpu/drm/amd/amdgpu/../pm/powerplay/hwmgr/smu7_hwmgr.c:3669:4
[ 13.349672] index 3 is out of range for type 'ATOM_Tonga_MCLK_Dependency_Record [1]'

[ 13.355130] ================================================================================
[ 13.355135] ================================================================================
[ 13.355138] UBSAN: array-index-out-of-bounds in /build/linux-SXblTa/linux-6.5.0/drivers/gpu/drm/amd/amdgpu/../pm/powerplay/hwmgr/smu7_hwmgr.c:3673:4
[ 13.355143] index 7 is out of range for type 'ATOM_Tonga_SCLK_Dependency_Record [1]'

It is worth noting that I have had performance issues on this GPU since before the upgrade to 23.10 as well. One can only hope that maybe fixing this will cause it to overclock properly while under load?