In the Linux kernel, the following vulnerability has been resolved: ipv6: mcast: remove one synchronize_net() barrier in ipv6_mc_down() As discussed in the past (commit 2d3916f31891 ("ipv6: fix skb drops in igmp6_event_query() and igmp6_event_report()")) I think the synchronize_net() call in ipv6_mc_down() is not needed. Under load, synchronize_net() can last between 200 usec and 5 ms. KASAN seems to agree as well.
Vulmon