Re: Debian SID kernel doesn't boot on PowerBook 3400c

On Tue, 3 Aug 2021, Christophe Leroy wrote:

Looks like the memory errors are linked to KUAP (Kernel Userspace Access 
Protection). Based on the places the problems happen, I don't think 
there are any invalid access, so there must be something wrong in the 
KUAP logic, probably linked to some interrupts happenning in kernel mode 
while the KUAP window is opened. And because is not selected by default 
on book3s/32 until 5.14, probably nobody ever tested it in a real 
environment before you.

I think the issue may be linked to commit 
https://github.com/linuxppc/linux/commit/c16728835 which happened 
between 5.12 and 5.13.

The messages, "Kernel attempted to write user page (c6207c) - exploit 
attempt? (uid: 0)", appear in the console logs generated by v5.13. Those 
logs come from the Powerbook G3 discussion in the other thread. Could that 
be the same bug?