From b6dd5acde3f165e364881c36de942c5b252e2a27 Mon Sep 17 00:00:00 2001 From: Madhuparna Bhowmik Date: Sat, 16 May 2020 13:15:15 +0530 Subject: [PATCH] ipv6: Fix suspicious RCU usage warning in ip6mr This patch fixes the following warning: ============================= WARNING: suspicious RCU usage 5.7.0-rc4-next-20200507-syzkaller #0 Not tainted ----------------------------- net/ipv6/ip6mr.c:124 RCU-list traversed in non-reader section!! ipmr_new_table() returns an existing table, but there is no table at init. Therefore the condition: either holding rtnl or the list is empty is used. Fixes: d1db275dd3f6e ("ipv6: ip6mr: support multiple tables") Reported-by: kernel test robot Suggested-by: Jakub Kicinski Signed-off-by: Madhuparna Bhowmik Signed-off-by: David S. Miller --- net/ipv6/ip6mr.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c index 65a54d74acc1..1e223e26f079 100644 --- a/net/ipv6/ip6mr.c +++ b/net/ipv6/ip6mr.c @@ -98,7 +98,8 @@ static void ipmr_expire_process(struct timer_list *t); #ifdef CONFIG_IPV6_MROUTE_MULTIPLE_TABLES #define ip6mr_for_each_table(mrt, net) \ list_for_each_entry_rcu(mrt, &net->ipv6.mr6_tables, list, \ - lockdep_rtnl_is_held()) + lockdep_rtnl_is_held() || \ + list_empty(&net->ipv6.mr6_tables)) static struct mr_table *ip6mr_mr_table_iter(struct net *net, struct mr_table *mrt) -- 2.11.0