Debian Security Advisory - xen Vulnerability : severa (DSA-2582-1)
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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
        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
        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
        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(), 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_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


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