Netfilter nft_set_elem_init Heap Overflow Privilege Escalation

An issue was discovered in the Linux kernel through 5.18.9.
A type confusion bug in nft_set_elem_init (leading to a buffer overflow)
could be used by a local attacker to escalate privileges.
The attacker can obtain root access, but must start with an unprivileged
user namespace to obtain CAP_NET_ADMIN access.
The issue exists in nft_setelem_parse_data in net/netfilter/nf_tables_api.c.