On Mon, Feb 25, 2019 at 8:48 AM Kees Cook <keescook@xxxxxxxxxxxx> wrote: > > On Sat, Feb 23, 2019 at 8:38 PM Andy Lutomirski <luto@xxxxxxxxxx> wrote: > > > > On Sat, Feb 23, 2019 at 4:44 PM Steven Rostedt <rostedt@xxxxxxxxxxx> wrote: > > > > > > On Sat, 23 Feb 2019 12:47:46 +0900 > > > Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote: > > > > > > > Since kprobes handler runs in IRQ context, we can not use access_ok() in it. > > > > (only on x86 + CONFIG_DEBUG_ATOMIC_SLEEP=y) > > > > > > Is it really IRQ context or exception context? That is, one > > > (interrupts) happen for any task, but exceptions happen because of the > > > software that is executed (like a breakpoint). Although you can have a > > > kprobe trigger in an interrupt handler (where user access wouldn't make > > > sense anyway). But there should be no problem with user access from an > > > exception handler. > > > > > > > Can we just get rid of this might_sleep()? access_ok() doesn't sleep > > as far as I know. > > We do need to be aware of the userfaultfd case of getting held by > userspace in the middle of a copy_*_user()... that's a whole other > problem. > I sure hope that pagefault_disable() already takes care of this. Otherwise we have major problems already.
