In the Linux kernel through 4.19, a use-after-free can occur due to a race condition between fanout_add from setsockopt and bind on an AF_PACKET socket. This issue exists because of the 15fe076edea787807a7cdc168df832544b58eba6 incomplete fix for a race condition. The code mishandles a certain multithreaded case involving a packet_do_bind unregister action followed by a packet_notifier register action. Later, packet_release operates on only one of the two applicable linked lists. The attacker can achieve Program Counter control.
https://blogs.securiteam.com/index.php/archives/3731
https://access.redhat.com/errata/RHSA-2020:0174
https://access.redhat.com/errata/RHSA-2019:4159
https://access.redhat.com/errata/RHSA-2019:3967
https://access.redhat.com/errata/RHSA-2019:1190
https://access.redhat.com/errata/RHSA-2019:1170
https://access.redhat.com/errata/RHSA-2019:0188