Published: 10 January 2011

The do_block_io_op function in (1) drivers/xen/blkback/blkback.c and (2) drivers/xen/blktap/blktap.c in Xen before 3.4.0 for the Linux kernel 2.6.18, and possibly other versions, allows guest OS users to cause a denial of service (infinite loop and CPU consumption) via a large production request index to the blkback or blktap back-end drivers. NOTE: some of these details are obtained from third party information.

From the Ubuntu security team

It was discovered that Xen did not correctly handle certain block requests. A local attacker in a Xen guest could cause the Xen host to use all available CPU resources, leading to a denial of service.




xen-3.1 has linux-2.6-xen-sparse/drivers/xen/blkback/blkback.c, but
xen-3.2 and xen-3.3 do not
marking dapper task as ignored since we no longer support xen
userspace on Dapper anyway
My feeling is that xen-3.1 has code affected, but does not package
that up. That would make only Hardy kernel code truely affected.
Oneiric not-affected for now (not containing blkback) and when we
move to upstream v3.0 is is fixed there.