CVE-2022-49137

In the Linux kernel, the following vulnerability has been resolved:

drm/amd/amdgpu/amdgpucs: fix refcount leak of a dmafence obj

This issue takes place in an error path in amdgpucsfencetohandleioctl(). When info->in.what falls into default case, the function simply returns -EINVAL, forgetting to decrement the reference count of a dmafence obj, which is bumped earlier by amdgpucsget_fence(). This may result in reference count leaks.

Fix it by decreasing the refcount of specific object before returning the error code.