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?
