CVE-2024-57901 af_packet: fix vlan_get_protocol_dgram() vs MSG_PEEK

In the Linux kernel, the following vulnerability has been resolved: afpacket: fix vlangetprotocoldgram vs MSGPEEK Blamed commit forgot MSGPEEK case, allowing a crash 1 as found by syzbot. Rework vlangetprotocoldgram to not touch skb at all, so that it can be used from many cpus on the same skb. A...