Citrix Xen 3.1.2

The fixup_page_fault function in arch/x86/traps.c in Xen 4.0.1 and earlier on 64-bit platforms, when paravirtualization is enabled, does not verify that kernel mode is used to call the handle_gdt_ldt_mapping_fault function, which allows guest OS users to cause a denial of service (host OS BUG_ON) via a crafted memory access.

The vbd_create function in Xen 3.1.2, when the Linux kernel 2.6.18 on Red Hat Enterprise Linux (RHEL) 5 is used, allows guest OS users to cause a denial of service (host OS panic) via an attempted access to a virtual CD-ROM device through the blkback driver. NOTE: some of these details are obtained from third party information.