In the Linux kernel, the following vulnerability has been resolved: net/openvswitch: check Ethernet header length in key_extract() When a

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

net/openvswitch: check Ethernet header length in key_extract()

When a packet arrives on an ARPHRD_NONE device (e.g. TUN),
ovs_flow_key_extract() trusts the user-provided skb->protocol field: if
it is ETH_P_TEB, the packet is classified as MAC_PROTO_ETHERNET and
key_extract() is called without ensuring the skb has ETH_HLEN (14) bytes
of linear data. key_extract() unconditionally pulls 2 * ETH_ALEN bytes
for MAC addresses and parse_ethertype() pulls 2 more, either of which
triggers a kernel BUG in __skb_pull() when the linear area is too small.

kernel BUG at include/linux/skbuff.h:2848!
RIP: 0010:key_extract+0xa7e/0xd90 net/openvswitch/flow.c:933
ovs_flow_key_extract+0x419/0xa70
ovs_vport_receive+0x222/0x390
netdev_frame_hook+0x3e0/0x630
tun_get_user+0x2d0c/0x38e0

Fixed by calling check_header() in key_extract() before accessing the
Ethernet header.