oss-security - CVE request - kvm: cat /dev/port in the guest can cause host DoS

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Message-ID: <4B67BA38.3090108@kernel.sg>
Date: Tue, 02 Feb 2010 13:38:00 +0800
From: Eugene Teo <eugeneteo@...nel.sg>
To: oss-security@...ts.openwall.com
CC: "Steven M. Christey" <coley@...us.mitre.org>
Subject: CVE request - kvm: cat /dev/port in the guest can cause host DoS

The problem is pit_state->channels[] has 3 elements, and pit_ioport_read 
uses "addr" as index to pit_get_count, so inb(0x43) reads (and 
potentially writes) into other data of kvm_kpit_state.

PIT control word (address 0x43) is write-only, reads are undefined.

Triggering this can cause a general protection fault on the host.

https://bugzilla.redhat.com/show_bug.cgi?id=560887
http://www.mail-archive.com/kvm@vger.kernel.org/msg28002.html

Thanks, Eugene
-- 
Eugene Teo / Red Hat Security Response Team

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