[Bug 2067862] Re: remove virtio legacy device make kernel Oops

** Also affects: linux (Ubuntu Noble)
Importance: Undecided
Status: New

** Changed in: linux (Ubuntu)
Status: New => Fix Released

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https://bugs.launchpad.net/bugs/2067862

Title:
remove virtio legacy device make kernel Oops

Status in linux package in Ubuntu:
Fix Released
Status in linux source package in Noble:
New

Bug description:
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).

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