XEN : Security Vulnerabilities, CVEs, (Denial of service)

The hypervisor_callback function in Xen, possibly before 3.4.0, as applied to the Linux kernel 2.6.30-rc4, 2.6.18, and probably other versions allows guest user applications to cause a denial of service (kernel oops) of the guest OS by triggering a segmentation fault in "certain address ranges."

Xen, possibly before 4.0.2, allows local 64-bit PV guests to cause a denial of service (host crash) by specifying user mode execution without user-mode pagetables.

The get_free_port function in Xen allows local authenticated DomU users to cause a denial of service or possibly gain privileges via unspecified vectors involving a new event channel port.

The instruction emulation in Xen 3.0.3 allows local SMP guest users to cause a denial of service (host crash) by replacing the instruction that causes the VM to exit in one thread with a different instruction in a different thread.

Xen, when using x86 Intel processors and the VMX virtualization extension is enabled, does not properly handle cpuid instruction emulation when exiting the VM, which allows local guest users to cause a denial of service (guest crash) via unspecified vectors.

Xen in the Linux kernel, when running a guest on a host without hardware assisted paging (HAP), allows guest users to cause a denial of service (invalid pointer dereference and hypervisor crash) via the SAHF instruction.

Off-by-one error in the __addr_ok macro in Xen 3.3 and earlier allows local 64 bit PV guest administrators to cause a denial of service (host crash) via unspecified hypercalls that ignore virtual-address bits.

Xen 4.1.1 and earlier allows local guest OS kernels with control of a PCI[E] device to cause a denial of service (CPU consumption and host hang) via many crafted DMA requests that are denied by the IOMMU, which triggers a livelock.

Buffer overflow in hw/scsi-disk.c in the SCSI subsystem in QEMU before 0.15.2, as used by Xen, might allow local guest users with permission to access the CD-ROM to cause a denial of service (guest crash) via a crafted SAI READ CAPACITY SCSI command. NOTE: this is only a vulnerability when root has manually modified certain permissions or ACLs.

Xen 3.4, 4.0, and 4.1, when the guest OS has not registered a handler for a syscall or sysenter instruction, does not properly clear a flag for exception injection when injecting a General Protection Fault, which allows local PV guest OS users to cause a denial of service (guest crash) by later triggering an exception that would normally be handled within Xen.

The PyGrub boot loader in Xen unstable before changeset 25589:60f09d1ab1fe, 4.2.x, and 4.1.x allows local para-virtualized guest users to cause a denial of service (memory consumption) via a large (1) bzip2 or (2) lzma compressed kernel image.

Xen 4.0, and 4.1, when running a 64-bit PV guest on "older" AMD CPUs, does not properly protect against a certain AMD processor bug, which allows local guest OS users to cause a denial of service (host hang) via sequential execution of instructions across a non-canonical boundary, a different vulnerability than CVE-2012-0217.

The handle_mmio function in arch/x86/hvm/io.c in the MMIO operations emulator for Xen 3.3 and 4.x, when running an HVM guest, does not properly reset certain state information between emulation cycles, which allows local guest OS users to cause a denial of service (guest OS crash) via unspecified operations on MMIO regions.

Xen 4.0 and 4.1 allows local HVM guest OS kernels to cause a denial of service (domain 0 VCPU hang and kernel panic) by modifying the physical address space in a way that triggers excessive shared page search time during the p2m teardown.

The set_debugreg hypercall in include/asm-x86/debugreg.h in Xen 4.0, 4.1, and 4.2, and Citrix XenServer 6.0.2 and earlier, when running on x86-64 systems, allows local OS guest users to cause a denial of service (host crash) by writing to the reserved bits of the DR7 debug control register.

The physdev_get_free_pirq hypercall in arch/x86/physdev.c in Xen 4.1.x and Citrix XenServer 6.0.2 and earlier uses the return value of the get_free_pirq function as an array index without checking that the return value indicates an error, which allows guest OS users to cause a denial of service (invalid memory write and host crash) and possibly gain privileges via unspecified vectors.

XENMEM_populate_physmap in Xen 4.0, 4.1, and 4.2, and Citrix XenServer 6.0.2 and earlier, when translating paging mode is not used, allows local PV OS guest kernels to cause a denial of service (BUG triggered and host crash) via invalid flags such as MEMF_populate_on_demand.

(1) TMEMC_SAVE_GET_CLIENT_WEIGHT, (2) TMEMC_SAVE_GET_CLIENT_CAP, (3) TMEMC_SAVE_GET_CLIENT_FLAGS and (4) TMEMC_SAVE_END in the Transcendent Memory (TMEM) in Xen 4.0, 4.1, and 4.2 allow local guest OS users to cause a denial of service (NULL pointer dereference or memory corruption and host crash) or possibly have other unspecified impacts via a NULL client id.

PHYSDEVOP_map_pirq in Xen 4.1 and 4.2 and Citrix XenServer 6.0.2 and earlier allows local HVM guest OS kernels to cause a denial of service (host crash) and possibly read hypervisor or guest memory via vectors related to a missing range check of map->index.

The GNTTABOP_swap_grant_ref sub-operation in the grant table hypercall in Xen 4.2 and Citrix XenServer 6.0.2 allows local guest kernels or administrators to cause a denial of service (host crash) and possibly gain privileges via a crafted grant reference that triggers a write to an arbitrary hypervisor memory location.

Xen 3.4 through 4.2, and possibly earlier versions, allows local guest OS administrators to cause a denial of service (Xen infinite loop and physical CPU consumption) by setting a VCPU with an "inappropriate deadline."

The (1) domain_pirq_to_emuirq and (2) physdev_unmap_pirq functions in Xen 2.2 allows local guest OS administrators to cause a denial of service (Xen crash) via a crafted pirq value that triggers an out-of-bounds read.

Xen 3.4 through 4.2, and possibly earlier versions, does not properly synchronize the p2m and m2p tables when the set_p2m_entry function fails, which allows local HVM guest OS administrators to cause a denial of service (memory consumption and assertion failure), aka "Memory mapping failure DoS vulnerability."

The HVMOP_pagetable_dying hypercall in Xen 4.0, 4.1, and 4.2 does not properly check the pagetable state when running on shadow pagetables, which allows a local HVM guest OS to cause a denial of service (hypervisor crash) via unspecified vectors.

Xen 4.0 through 4.2, when running 32-bit x86 PV guests on 64-bit hypervisors, allows local guest OS administrators to cause a denial of service (infinite loop and hang or crash) via invalid arguments to GNTTABOP_get_status_frames, aka "Grant table hypercall infinite loop DoS vulnerability."