Commit b6dd5acd authored May 16, 2020 by Madhuparna Bhowmik Committed by David S. Miller May 16, 2020

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: d1db275d ("ipv6: ip6mr: support multiple tables")
Reported-by: kernel test robot <lkp@intel.com>
Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent f85c1598

net/ipv6/ip6mr.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -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)

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