Overview
About vulnerability
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.
Details
- Affected product:
- Debian 10 ELS
- Affected packages:
- linux @ 4.19.0