Date: Mon, 30 Nov 2015 13:33:03 -0800 From: Kees Cook <keescook@...omium.org> To: "H. Peter Anvin" <hpa@...or.com> Cc: Ingo Molnar <mingo@...nel.org>, Andy Lutomirski <luto@...capital.net>, Linus Torvalds <torvalds@...ux-foundation.org>, PaX Team <pageexec@...email.hu>, "kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>, Mathias Krause <minipli@...glemail.com>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...hat.com>, Thomas Gleixner <tglx@...utronix.de>, x86-ml <x86@...nel.org>, Arnd Bergmann <arnd@...db.de>, Michael Ellerman <mpe@...erman.id.au>, linux-arch <linux-arch@...r.kernel.org>, Emese Revfy <re.emese@...il.com> Subject: Re: [PATCH 0/2] introduce post-init read-only memory On Mon, Nov 30, 2015 at 1:14 PM, H. Peter Anvin <hpa@...or.com> wrote: > On 11/29/15 00:05, Ingo Molnar wrote: >> >> * Andy Lutomirski <luto@...capital.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. >> > > 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. :) -Kees -- Kees Cook Chrome OS & Brillo Security
Powered by blists - more mailing lists
Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.