Description: net/packet: fix overflow in tpacket_rcv
References:
 https://www.openwall.com/lists/oss-security/2020/09/03/3
Notes:
Bugs:
upstream: needed
4.19-upstream-stable: needed
4.9-upstream-stable: needed
sid: needed
4.19-buster-security: needed
4.9-stretch-security: needed