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

xen/netback: Fix buffer overrun triggered by unusual packet

It is possible that a guest can send a packet that contains a head + 18
slots and yet has a len <= XEN_NETBACK_TX_COPY_LEN. This causes nr_slots
to underflow in xenvif_get_requests() which then causes the subsequent
loop's termination condition to be wrong, causing a buffer overrun of
queue->tx_map_ops.

Rework the code to account for the extra frag_overflow slots.

This is CVE-2023-34319 / XSA-432.