drivers/vhost/net.c in the Linux kernel before 3.13.10, when mergeable buffers are disabled, does not properly validate packet lengths, which allows guest OS users to cause a denial of service (memory corruption and host OS crash) or possibly gain privileges on the host OS via crafted packets, related to the handle_rx and get_rx_bufs functions.
https://github.com/torvalds/linux/commit/d8316f3991d207fe32881a9ac20241be8fa2bad0