Race condition in net/packet/af_packet.c in the Linux kernel before 4.9.13 allows local users to cause a denial of service (use-after-free) or possibly have unspecified other impact via a multithreaded application that makes PACKET_FANOUT setsockopt system calls. It was discovered that a race condition existed in the AF_PACKET handling code in the Linux kernel. A local attacker could use this to cause a denial of service (system crash) or possibly execute arbitrary code.