CVE-2022-26356

Racy interactions between dirty vram tracking and paging log dirty
hypercalls Activation of log dirty mode done by XEN_DMOP_track_dirty_vram
(was named HVMOP_track_dirty_vram before Xen 4.9) is racy with ongoing log
dirty hypercalls. A suitably timed call to XEN_DMOP_track_dirty_vram can
enable log dirty while another CPU is still in the process of tearing down
the structures related to a previously enabled log dirty mode
(XEN_DOMCTL_SHADOW_OP_OFF). This is due to lack of mutually exclusive
locking between both operations and can lead to entries being added in
already freed slots, resulting in a memory leak.

Notes