Messages in this thread | | | Date | Sun, 29 Nov 2015 09:05:05 +0100 | From | Ingo Molnar <> | Subject | Re: [kernel-hardening] [PATCH 0/2] introduce post-init read-only memory |
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* Andy Lutomirski <luto@amacapital.net> 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.
Thanks,
Ingo
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