In the Linux kernel, the following vulnerability has been resolved:
drm/vmwgfx: fix guest_memory_dirty bitfield clobbered as size
Two sites in vmwgfx_resource.c assign boolean literals to
res->guest_memory_size, which is an unsigned long allocation-size
field; the intended target is the adjacent res->guest_memory_dirty
bitfield. After the assignments the field holds 0 or 1 instead of
the resource's MOB allocation size:
- vmw_resource_release() writes 0 (false), and
- vmw_resource_unbind_list() writes 1 (true).
Subsequent revalidation paths read guest_memory_size when computing
the dirty page range (vmw_bo_dirty_transfer_to_res()) and the buffer
allocation size (vmw_resource_buf_alloc()), producing zero-length
walks or wrap-around ranges that read or write past the MOB bitmap.
The dirty-tracking intent of the original code (mark the resource as
dirtied since the last sync) is also lost, since guest_memory_dirty
is never updated.
Rename both assignments to guest_memory_dirty.