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             AUSCERT External Security Bulletin Redistribution

                            xen security update
                             10 December 2012


        AusCERT Security Bulletin Summary

Product:           xen
Publisher:         Debian
Operating System:  Debian GNU/Linux 6
Impact/Access:     Denial of Service    -- Existing Account
                   Increased Privileges -- Existing Account
Resolution:        Patch/Upgrade
CVE Names:         CVE-2012-5515 CVE-2012-5514 CVE-2012-5513
                   CVE-2012-5510 CVE-2012-4539 CVE-2012-4538
                   CVE-2012-4537 CVE-2012-4535 CVE-2011-3131

Reference:         ESB-2012.1150

Original Bulletin: 

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Debian Security Advisory DSA-2582-1                   security@debian.org
http://www.debian.org/security/                         Yves-Alexis Perez
December 07, 2012                      http://www.debian.org/security/faq
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Package        : xen
Vulnerability  : several
Problem type   : local
Debian-specific: no
CVE ID         : CVE-2011-3131 CVE-2012-4535 CVE-2012-4537 CVE-2012-4538 
                 CVE-2012-4539 CVE-2012-5510 CVE-2012-5513 CVE-2012-5514
Debian Bug     : 

Multiple denial of service vulnerabilities have been discovered in the xen
hypervisor. One of the issue (CVE-2012-5513) could even lead to privilege
escalation from guest to host.

Some of the recently published Xen Security Advisories (XSA 25 and 28) are not
fixed by this update and should be fixed in a future release.

CVE-2011-3131 (XSA 5): DoS using I/OMMU faults from PCI-passthrough guest

	A VM that controls a PCI[E] device directly can cause it to issue DMA
	requests to invalid addresses. Although these requests are denied by the
	I/OMMU, the hypervisor needs to handle the interrupt and clear the error from
	the I/OMMU, and this can be used to live-lock a CPU and potentially hang the

CVE-2012-4535 (XSA 20): Timer overflow DoS vulnerability

	A guest which sets a VCPU with an inappropriate deadline can cause an
	infinite loop in Xen, blocking the affected physical CPU indefinitely.

CVE-2012-4537 (XSA 22): Memory mapping failure DoS vulnerability

	When set_p2m_entry fails, Xen's internal data structures (the p2m and m2p
	tables) can get out of sync. This failure can be triggered by unusual guest
	behaviour exhausting the memory reserved for the p2m table. If it happens,
	subsequent guest-invoked memory operations can cause Xen to fail an assertion
	and crash.

CVE-2012-4538 (XSA 23): Unhooking empty PAE entries DoS vulnerability

	The HVMOP_pagetable_dying hypercall does not correctly check the
	caller's pagetable state, leading to a hypervisor crash.

CVE-2012-4539 (XSA 24): Grant table hypercall infinite loop DoS vulnerability

	Due to inappropriate duplicate use of the same loop control variable,
	passing bad arguments to GNTTABOP_get_status_frames can cause an
	infinite loop in the compat hypercall handler.

CVE-2012-5510 (XSA 26): Grant table version switch list corruption vulnerability

	Downgrading the grant table version of a guest involves freeing its status
	pages. This freeing was incomplete - the page(s) are freed back to the
	allocator, but not removed from the domain's tracking list. This would cause
	list corruption, eventually leading to a hypervisor crash.

CVE-2012-5513 (XSA 29): XENMEM_exchange may overwrite hypervisor memory

	The handler for XENMEM_exchange accesses guest memory without range checking
	the guest provided addresses, thus allowing these accesses to include the
	hypervisor reserved range.
	A malicious guest administrator can cause Xen to crash. If the out of address
	space bounds access does not lead to a crash, a carefully crafted privilege
	escalation cannot be excluded, even though the guest doesn't itself control
	the values written.

CVE-2012-5514 (XSA 30): Broken error handling in guest_physmap_mark_populate_on_demand()

	guest_physmap_mark_populate_on_demand(), before carrying out its actual
	operation, checks that the subject GFNs are not in use. If that check fails,
	the code prints a message and bypasses the gfn_unlock() matching the
	gfn_lock() carried out before entering the loop.
	A malicious guest administrator can then use it to cause Xen to hang.

CVE-2012-5515 (XSA 31): Several memory hypercall operations allow invalid extent order values

	Allowing arbitrary extent_order input values for XENMEM_decrease_reservation,
	XENMEM_populate_physmap, and XENMEM_exchange can cause arbitrarily long time
	being spent in loops without allowing vital other code to get a chance to
	execute. This may also cause inconsistent state resulting at the completion
	of these hypercalls.

For the stable distribution (squeeze), these problems have been fixed in
version 4.0.1-5.5.

For the testing distribution (wheezy), these problems have been fixed in
version 4.1.3-6.

For the unstable distribution (sid), these problems have been fixed in
version 4.1.3-6.

We recommend that you upgrade your xen packages.

Further information about Debian Security Advisories, how to apply
these updates to your system and frequently asked questions can be
found at: http://www.debian.org/security/

Mailing list: debian-security-announce@lists.debian.org
Version: GnuPG v2.0.19 (GNU/Linux)


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