Broadcom wireless working, but error when booting


I have an old dell Inspiron 5748 laptop, installed Lubuntu. (Full wipe and install via usb.) Installed the bcmwl-kernel-source, as recommended by the following link:

jperrin@john-inspiron5748:~$ lspci -nn -d 14e4:
06:00.0 Network controller [0280]: Broadcom Inc. and subsidiaries BCM43142 802.11b/g/n [14e4:4365] (rev 01)

Wireless works great, but I get the following error on booting, if I remove the broadcom-wireless-drivers then the error message goes away:

dmesg entry

[ 39.659777] kernel: UBSAN: array-index-out-of-bounds in /var/lib/dkms/bcmwl/
[ 39.659788] kernel: index 2 is out of range for type 'ether_addr [1]'

syslog entry

Mar 17 11:02:58 john-inspiron5748 kernel: [ 39.659777] UBSAN: array-index-out-of-bounds in /var/lib/dkms/bcmwl/
Mar 17 11:02:58 john-inspiron5748 kernel: [ 39.659788] index 2 is out of range for type 'ether_addr [1]'
Mar 17 11:02:58 john-inspiron5748 kernel: [ 39.659795] CPU: 1 PID: 613 Comm: avahi-daemon Tainted: P OE 6.5.0-25-generic #25~22.04.1-Ubuntu
jperrin@john-inspiron5748:~$ uname -a
Linux john-inspiron5748 6.5.0-25-generic #25~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Tue Feb 20 16:09:15 UTC 2 x86_64 x86_64 x86_64 GNU/Linux

Any ideas or what to check would be appreciated. Laptop works great with Lubuntu. Good to resurrect my dad’s old laptop.

Thank you!

I see many complaints about this across many different files. No clear solution that I found in a cursory search.

This bug has a patch and while it seems very similar, it’s not exactly the same so not sure it would work. It’s also not an approved solution, per se.


It looks like it might be the same issue I have, but as you state it is not approved and I also would have no idea how to apply the patch as well. Will wait and see.

Thank you1


Still looking for a resolution to this. Have seen similar issues elsewhere, but nothing that has a fix so far. It is not a major issue luckily, just slightly annoying when booting. Still love lubuntu! I don’t use it everyday, but when I need to,it is working great.

Actually, reading a little more, I’m convinced that bug and its patch is the same issue.

For a little context, UBSan is the Undefined Behavior Sanitizer. This article describes in good detail what it does, but the tl;dr is that it issues warnings when careless programming leads to the potential for undefined behavior to occur.

In this case, the issue is using the pre-C99 method for declaring an array of undefined size, which is array[0] or array[1]. Obviously, that means declaring an array of size 0 or size 1, which is certainly not the same as declaring an undefined size. As the link to the patch describes, “This was technically always wrong.” More detail can be found here.

The issue has been there a long time, but there are two reasons why these warnings are popping up all of a sudden:

  1. A change in Ubuntu 23.04 to enable UBSan by default
  2. A change in UBSan in the 6.5 kernel (new to Ubuntu 23.10) specifically about these array issues

So what this turns out to be is a warning. Nothing more. So no worries.

I will point out that you appear to be using the proprietary Broadcom driver. I suspect you probably have to. The good news is it works. The bad news is that you usually have to wait on Broadcom to deliver solutions to bugs, in general. Similar issues occur with proprietary NVIDIA drivers, and as you can see here from their forums, they don’t seem to care enough to fix this issue. That said, I’d just ignore the warnings.


Wow, very good explanation about the issue I am having. I appreciate it. Yes, have to use the broadcom driver, when I remove it the error message goes away. Of course so does my wireless. Guess I will live with it until broadcom fixes it! Doubt they will, but one can dream.

Thank you!

1 Like