Overview
About vulnerability
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.
Details
- Affected product:
- AlmaLinux 9.2 ESU , Amazon Linux 2 ELS , CentOS 8.4 ELS , CentOS 8.5 ELS , CentOS Stream 8 ELS , Debian 10 ELS , Oracle Linux 7 ELS , TuxCare 9.6 ESU , Ubuntu 16.04 ELS , Ubuntu 18.04 ELS , Ubuntu 20.04 ELS
- Affected packages:
- kernel @ 4.18.0 (+12 more)
Fixes
KernelCare state
Live-patch status from KernelCare for each operating system.
| Operating system | Status | Covered kernels |
|---|---|---|
| Debian 11 | Planned | — |
| Debian 11 cloud | Planned | — |
| Debian 13 | Planned | — |
| Ubuntu 22.04 | Planned | — |
| Ubuntu 24.04 | Planned | — |
| Ubuntu 24.04 AWS | Planned | — |