Messages in this thread | | | Date | Sun, 5 Oct 2008 10:01:17 -0700 | From | Arjan van de Ven <> | Subject | Re: [RFC PATCH 02/12] On Tue, 23 Sep 2008, David Miller wrote: |
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On Sun, 5 Oct 2008 18:16:29 +0200 (CEST) Thomas Gleixner <tglx@linutronix.de> wrote:
> On Sun, 5 Oct 2008, Arjan van de Ven wrote: > > On Sun, 5 Oct 2008 17:55:14 +0200 (CEST) > > Thomas Gleixner <tglx@linutronix.de> wrote: > > > > > On Sun, 5 Oct 2008, Arjan van de Ven wrote: > > > > Thomas Gleixner wrote: > > > > > On Sat, 4 Oct 2008, Jesse Brandeburg wrote: > > > > > > > Exactly. The access to a ro region results in a fault. I > > > > > > > have nowhere seen that trigger, but I can reproduce the > > > > > > > trylock() WARN_ON, which confirms that there is > > > > > > > concurrent access to the NVRAM registers. The backtrace > > > > > > > pattern is similar to the one you have seen. > > > > > > are you still getting WARN_ON *with* all the mutex based > > > > > > fixes already applied? > > > > > > > > > > The WARN_ON triggers with current mainline. Is there any > > > > > fixlet in Linus tree missing ? > > > > > > > > > > > with the mutex patches in place (without protection patch) > > > > > > we are still reproducing the issue, until we apply the > > > > > > set_memory_ro patch. > > > > > > > > > > That does not make sense to me. If the memory_ro patch is > > > > > providing _real_ protection then you _must_ run into an access > > > > > violation. If not, then the patch just papers over the real > > > > > problem in some mysterious way. > > > > > > > > > > > > > not if the bad code is doing copy_to_user .... (or similar) > > > > > > You mean: copy_from_user :) This would require that the e1000e > > > nvram region is writable via copy_from_user by an e1000e user > > > space interface. A quick grep does not reviel such a horrible > > > interface. > > > > I meant a "copy_to_user" to a duff pointer, somewhere in the kernel. > > Hmm, don't we check the *to address on copy_to_user ? >
fair point
and we do exception catching for copy_from_user as well on the source, just by how it's implemented
-- Arjan van de Ven Intel Open Source Technology Centre For development, discussion and tips for power savings, visit http://www.lesswatts.org
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