CVE-2025-38413

In the Linux kernel, the following vulnerability has been resolved:

virtio-net: xsk: rx: fix the frame's length check

When calling buf_to_xdp, the len argument is the frame data's length without virtio header's length (vi->hdr_len). We check that len with

xsk_pool_get_rx_frame_size() + vi->hdr_len

to ensure the provided len does not larger than the allocated chunk size. The additional vi->hdr_len is because in virtnet_add_recvbuf_xsk, we use part of XDP_PACKET_HEADROOM for virtio header and ask the vhost to start placing data from

hard_start + XDP_PACKET_HEADROOM - vi->hdr_len

not hard_start + XDP_PACKET_HEADROOM

But the first buffer has virtio_header, so the maximum frame's length in the first buffer can only be

xsk_pool_get_rx_frame_size()

not xsk_pool_get_rx_frame_size() + vi->hdr_len

like in the current check.

This commit adds an additional argument to buf_to_xdp differentiate between the first buffer and other ones to correctly calculate the maximum frame's length.

This vulnerability is rated as Moderate impact because triggering it requires an environment where virtio-net devices are explicitly configured to handle packet reception via AF_XDP zero-copy sockets. Under default Red Hat Enterprise Linux configurations, this specialized high-speed networking path is not active, substantially restricting the blast radius to custom packet-processing workloads. Additionally, Red Hat Enterprise Linux 8 and 9 do not include the vulnerable zero-copy implementation in the virtio-net driver and are therefore unaffected.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.