In the Linux kernel, the following vulnerability has been resolved:
drm/prime: Fix use after free in mmap with drm_gem_ttm_mmap
drm_gem_ttm_mmap() drops a reference to the gem object on success. If the gem objects refcount == 1 on entry to drm_gem_prime_mmap(), that drop will free the gem object, and the subsequent drm_gem_object_get() will be a UAF. Fix by grabbing a reference before calling the mmap helper.
This issue was forseen when the reference dropping was adding in commit 9786b65bc61ac (drm/ttm: fix mmap refcounting): For that to work properly the drm_gem_object_get() call in drm_gem_ttm_mmap() must be moved so it happens before calling obj->funcs->mmap(), otherwise the gem refcount would go down to zero.