On Thu, Mar 25, 2021 at 05:02:34PM -0700, Tony Luck wrote:
> Andy Lutomirski pointed out that sending SIGBUS to tasks that
> hit poison in the kernel copying syscall parameters from user
> address space is not the right semantic.
What does that mean exactly?
>From looking at the code, that is this conditional:
if (t == EX_HANDLER_UACCESS && regs && is_copy_from_user(regs)) {
m->kflags |= MCE_IN_KERNEL_RECOV;
m->kflags |= MCE_IN_KERNEL_COPYIN;
so what does the above have to do with syscall params?
If it is about us being in ring 0 and touching user memory and eating
poison in same *user* memory while doing so, then sure, that makes
sense.
> So stop doing that. Add a new kill_me_never() call back that
> simply unmaps and offlines the poison page.
Right, that's the same as handling poisoned user memory.
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
