Comment 0 for bug 2067862

In the Ubuntu 24's 6.8.0-31-generic kernel version, the capability https://github.com/torvalds/linux/commit/fd27ef6b44bec26915c5b2b22c13856d9f0ba17a (virtio-pci: Introduce admin virtqueue) was added. However, an issue was overlooked by the upstream community, which is that if the virtio device is not a modern virtio device, but a legacy virtio device, the is_avq function pointer is not assigned, resulting in a NULL pointer for the is_avq function pointer in the virtio_pci_device structure of the legacy virtio device. When unloading the virtio device, if the code calls if (vp_dev->is_avq(vdev, vq->index)), the RIP register of the CPU points to a NULL pointer address.

I have noticed that the kernel community has already included a related solution, and I hope that the Ubuntu kernel can backport to support the remove operation for legacy virtio devices: https://github.com/torvalds/linux/commit/c8fae27d141a32a1624d0d0d5419d94252824498 (virtio-pci: Check if is_avq is NULL).