In the Linux kernel, the following vulnerability has been resolved:

netfilter: nfnetlink log: wait for rcu grace period before freeing pernet state

sashiko reports: "nfnl log net exit() calls nf log unset(), which clears the logger pointer without an RCU grace period. Immediately after, ops free list() frees the per-net state while concurrent packets might still be executing nf log packet() under rcu read lock()."

Clear the pointer via .pre exit to make sure rcu readers have completed before pernet storage is free'd. The change in nf log syslog.c is only done for consistency: it doesn't use pernet data.