Messages in this thread | | | Date | Wed, 26 Dec 2007 21:49:25 +0100 | From | Pavel Machek <> | Subject | Re: [PATCH] x86_64: fix problems due to use of "outb" to port 80 on some AMD64x2 laptops, etc. |
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On Sun 2007-12-16 15:34:58, H. Peter Anvin wrote: > Pavel Machek wrote: >> Hi! >>> The process of safely making delicate changes here is beyond my >>> responsibility as just a user - believe me, I'm not suggesting that a >>> risky fix be put in .24. I can patch my own kernels, and I can even >>> share an unofficial patch with others for now, or suggest that Fedora and >>> Ubuntu add it to their downstream. >>> >>> May I make a small suggestion, though. If the decision is a DMI-keyed >>> switch from out-80 to udelay(2) gets put in, perhaps there should also >>> be a way for people to test their own configuration for the underlying >>> problem made available as a script. Though it is a "hack", all you need >>> to freeze a problem system is to run a loop doing about 1000 "cat >>> /dev/nvram > /dev/null" commands. If that leads to a freeze, one might >>> ask to have the motherboard added to the DMI-key list. >> Can you freeze it by catting /dev/rtc, too? That may be significant, >> because that is readable for group audio (at least on some >> systems)... which would smell like "small security hole" to me. > > Heck, on my system (Fedora 7), it's mode 644...
Ok, time to CC security team, I'd say.
Problem is, that some AMD64x2 nVidia laptops crash on port 0x80 access... which is easily user-triggerable by using /dev/rtc. If it is 644 on Fedora, I guess we have a problem.
Otoh, it is "only" a denial of service, and it can probably be attributed to "buggy hardware". Is that still relevant for security team?
Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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