Linux/xen-netfront: Memory leak due to missing cleanup function

ISSUE DESCRIPTION

In netfront, xennet_alloc_one_rx_buffer() failed to call the appropriate clean-up function, resulting in a memory leak.

IMPACT

A malicious guest userspace process can exhaust memory resources within the guest kernel, potentially leading to a guest crash (Denial of Service). It is not known whether it can be triggered remotely.

VULNERABLE SYSTEMS

Systems with guests running Linux 5.9 and later with Xen PV network devices are affected.