CVE-2025-21977 fbdev: hyperv_fb: Fix hang in kdump kernel when on Hyper-V Gen 2 VMs

In the Linux kernel, the following vulnerability has been resolved: fbdev: hypervfb: Fix hang in kdump kernel when on Hyper-V Gen 2 VMs Gen 2 Hyper-V VMs boot via EFI and have a standard EFI framebuffer device. When the kdump kernel runs in such a VM, loading the efifb driver may hang because of...