On Thu, May 1, 2014 at 2:15 PM, Andi Kleen <a...@firstfloor.org> wrote: >> If usergs == kernelgs, then ebx will always be 1 and we'll never end >> up in paranoid_userspace. > > You may miss a reschedule in this obscure case. It shouldn't really > happen because loading a kernel pointer is not useful for user space. > > Doesn't seem like a real issue to me. > > We only happen need to handle it to avoid crashing.
Allowing userspace to prevent itself from being rescheduled by loading something strange into gsbase seems unfortunate. --Andy > >> Alternatively, what if the paranoid entry checked whether we're coming >> from userspace at the very beginning and, if so, just jumped to the >> non-paranoid entry? > > That would work, but I doubt it would be worth it. > > -Andi -- Andy Lutomirski AMA Capital Management, LLC -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
