CVE-2023-54232 m68k: Only force 030 bus error if PC not in exception table

Not scored Published 30 Dec 2025 Updated 11 May 2026

A local attacker can trigger a kernel panic on m68k systems by forcing a bus error during sysrq-triggered backtraces, causing denial of service.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is CVE-2023-54232?

CVE-2023-54232 is a denial of service vulnerability in Linux, published on 30 Dec 2025. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

In the Linux kernel, the following vulnerability has been resolved:

m68k: Only force 030 bus error if PC not in exception table

__get_kernel_nofault() does copy data in supervisor mode when forcing a task backtrace log through /proc/sysrq_trigger. This is expected cause a bus error exception on e.g. NULL pointer dereferencing when logging a kernel task has no workqueue associated. This bus error ought to be ignored.

Our 030 bus error handler is ill equipped to deal with this:

Whenever ssw indicates a kernel mode access on a data fault, we don't even attempt to handle the fault and instead always send a SEGV signal (or panic). As a result, the check for exception handling at the fault PC (buried in send_sig_fault() which gets called from do_page_fault() eventually) is never used.

In contrast, both 040 and 060 access error handlers do not care whether a fault happened on supervisor mode access, and will call do_page_fault() on those, ultimately honoring the exception table.

Add a check in bus_error030 to call do_page_fault() in case we do have an entry for the fault PC in our exception table.

I had attempted a fix for this earlier in 2019 that did rely on testing pagefault_disabled() (see link below) to achieve the same thing, but this patch should be more generic.

Tested on 030 Atari Falcon.

Which versions are affected by CVE-2023-54232?

How do I fix CVE-2023-54232?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2023-54232 being exploited?

There is no known exploitation of CVE-2023-54232 in the wild and no public exploit code.

Sources

Also known as BELL-CVE-2023-54232, DEBIAN-CVE-2023-54232, GHSA-gvjr-wrwm-xp44, UBUNTU-CVE-2023-54232.