oss-security - CVE request: kernel: KVM: x86 emulator: limit instructions to 15 bytes

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Message-ID: <4B0CE4D5.1040106@kernel.sg>
Date: Wed, 25 Nov 2009 16:03:33 +0800
From: Eugene Teo <eugeneteo@...nel.sg>
To: oss-security@...ts.openwall.com
CC: "Steven M. Christey" <coley@...us.mitre.org>
Subject: CVE request: kernel: KVM: x86 emulator: limit instructions to 15
 bytes

Quoting from the patch: "While we are never normally passed an 
instruction that exceeds 15 bytes, smp games can cause us to attempt to 
interpret one, which will cause large latencies in non-preempt hosts."

http://git.kernel.org/?p=linux/kernel/git/avi/kvm.git;a=commitdiff;h=e42d9b8141d1f54ff72ad3850bb110c95a5f3b88
https://bugzilla.redhat.com/show_bug.cgi?id=541160

I understand that a malicious guest can cause long scheduling latencies 
in the host, resulting in a denial of service, but I have not 
investigated this further to determine if it has more severe consequences.

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

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