On Mon, Nov 30, 2015 at 1:33 PM, Kees Cook <keescook@xxxxxxxxxxxx> wrote: > On Mon, Nov 30, 2015 at 1:14 PM, H. Peter Anvin <hpa@xxxxxxxxx> wrote: >> On 11/29/15 00:05, Ingo Molnar wrote: >>> >>> * Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote: >>> >>>>>> - print a warning and a backtrace, and just mark the page read-write >>>>>> so that the machine survives, but we get notified and can fix whatever >>>>>> broken code >>>>> >>>>> This seems very easy to add. Should I basically reverse the effects of >>>>> mark_rodata_ro(), or should I only make the new ro-after-init section as RW? >>>>> (I think the former would be easier.) >>>> >>>> I'd suggest verifying that the page in question is .data..ro_after_init and, if >>>> so, marking that one page RW. >>> >>> Yes, this was PaX's suggestion as well, and I agree: doing that turns a quite >>> possibly unrecoverable boot/shutdown time or suspend/resume time (suspend is >>> really a special category of 'bootup') crasher oops into a more informative stack >>> dump. >>> >>> These ro related faults tend to trigger when init/deinit is running, and oopsing >>> in those sequences is typically a lot less survivable than say oopsing in a high >>> level system call while not holding locks. >>> >> >> I think what should do is have a debug option which can be set to "rw", >> "log" or "oops"; the latter should probably be the default. > > Can someone write that patch, and then I will include it in the > series? I haven't touched fault handler code, and it would be faster > if someone more familiar with that area did it. :) I think I can do it in a week or two if no one beats me to it. --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
