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SYNTHESIS OF THE VULNERABILITY

An attacker can use a freed memory area in the pirq_guest_bind()
function of Xen, in order to trigger a denial of service, and
possibly to execute code.

– Impacted products: Fedora, Unix (platform)
– Severity: 2/4
– Creation date: 23/01/2014

DESCRIPTION OF THE VULNERABILITY

A Xen system can be configured:
– with a PCI device in Passthrough for guest systems
– with more than 128 processors (64 bit), or with more than 64
processors (32 bit)

However, in this configuration, a guest administrator can change
the IRQ of the PCI device, in order to trigger an error in the
pirq_guest_bind() function of the xen/arch/x86/irq.c file. A
memory area is then freed twice.

An attacker can therefore use a freed memory area in the
pirq_guest_bind() function of Xen, in order to trigger a denial of
service, and possibly to execute code.

ACCESS TO THE COMPLETE VIGIL@NCE BULLETIN

http://vigilance.fr/vulnerability/Xen-use-after-free-via-pirq-guest-bind-14127