The virtnet_probe function in drivers/net/virtio_net.c in the Linux kernel before 4.2 attempts to support a FRAGLIST feature without proper memory allocation, which allows guest OS users to cause a denial of service (buffer overflow and memory corruption) via a crafted sequence of fragmented packets. http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2015-5156