CVE-2023-54232

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> m68k: Only force 030 bus error if PC not in exception table<br /> <br /> __get_kernel_nofault() does copy data in supervisor mode when<br /> forcing a task backtrace log through /proc/sysrq_trigger.<br /> This is expected cause a bus error exception on e.g. NULL<br /> pointer dereferencing when logging a kernel task has no<br /> workqueue associated. This bus error ought to be ignored.<br /> <br /> Our 030 bus error handler is ill equipped to deal with this:<br /> <br /> Whenever ssw indicates a kernel mode access on a data fault,<br /> we don&amp;#39;t even attempt to handle the fault and instead always<br /> send a SEGV signal (or panic). As a result, the check<br /> for exception handling at the fault PC (buried in<br /> send_sig_fault() which gets called from do_page_fault()<br /> eventually) is never used.<br /> <br /> In contrast, both 040 and 060 access error handlers do not<br /> care whether a fault happened on supervisor mode access,<br /> and will call do_page_fault() on those, ultimately honoring<br /> the exception table.<br /> <br /> Add a check in bus_error030 to call do_page_fault() in case<br /> we do have an entry for the fault PC in our exception table.<br /> <br /> I had attempted a fix for this earlier in 2019 that did rely<br /> on testing pagefault_disabled() (see link below) to achieve<br /> the same thing, but this patch should be more generic.<br /> <br /> Tested on 030 Atari Falcon.