CVE-2026-45890
Description
In the Linux kernel, the following vulnerability has been resolved:
xen-netback: reject zero-queue configuration from guest
A malicious or buggy Xen guest can write '0' to the xenbus key
'multi-queue-num-queues'. The connect() function in the backend only
validates the upper bound (requested_num_queues > xenvif_max_queues)
but not zero, allowing requested_num_queues=0 to reach
vzalloc(array_size(0, sizeof(struct xenvif_queue))), which triggers
WARN_ON_ONCE(!size) in __vmalloc_node_range().
On systems with panic_on_warn=1, this allows a guest-to-host denial
of service.
The Xen network interface specification requires
the queue count to be 'greater than zero'.
Add a zero check to match the validation already present
in xen-blkback, which has included this
guard since its multi-queue support was added.