When dumping sets in order to create the proper order for restore, the list type of sets dumped last. Therefore internally we run the dumping loop twice: first with all non-list type of sets and skipping the list type ones and then secondly for the list type of sets. Sashiko noticed that there's a potential race between dump and destroy if in the first loop the last set was a list type of set: its pointer remains unreferenced and a concurrent destroy can free it. Fix the issue by resetting the variable holding the pointer. Signed-off-by: Jozsef Kadlecsik --- net/netfilter/ipset/ip_set_core.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/netfilter/ipset/ip_set_core.c b/net/netfilter/ipset/ip_set_core.c index c5a26236a0bb..0874029cb0f2 100644 --- a/net/netfilter/ipset/ip_set_core.c +++ b/net/netfilter/ipset/ip_set_core.c @@ -1613,6 +1613,7 @@ ip_set_dump_do(struct sk_buff *skb, struct netlink_callback *cb) ((dump_type == DUMP_ALL) == !!(set->type->features & IPSET_DUMP_LAST))) { write_unlock_bh(&ip_set_ref_lock); + set = NULL; continue; } pr_debug("List set: %s\n", set->name); -- 2.39.5