Date: Wed, 29 Jun 2011 15:58:03 -0400 (EDT) From: Josh Bressers <bressers@...hat.com> To: oss-security@...ts.openwall.com Cc: "Steven M. Christey" <coley@...us.mitre.org> Subject: Re: CVE request: qemu-kvm: OOB memory access caused by negative vq notifies Please use CVE-2011-2512. Thanks. -- JB ----- Original Message ----- > The virtio_queue_notify() function checks that the virtqueue number is > less than the maximum number of virtqueues. A signed comparison is > used but the virtqueue number could be negative if a buggy or > malicious > guest is run. This results in memory accesses outside of the virtqueue > array. > > To trigger this issue the attacker needs to issue 32bit write to Queue > Notify field of Virtio Header in the virtio pci config space even > though > the field is 16bit only by specs. Qemu-kvm allows that for the moment > and provides whole 32bit value to the underlying functions. > > Unprivileged guest user could use this flaw to crash the guest (denial > of service) or, possibly, escalate their privileges on the host. > > Upstream patch: > http://patchwork.ozlabs.org/patch/94604/ > > References: > https://bugzilla.redhat.com/show_bug.cgi?id=717399 > http://patchwork.ozlabs.org/patch/94604/ > > Thanks, > -- > Petr Matousek / Red Hat Security Response Team
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