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Commit 2e4b2aeb authored by Paolo Abeni's avatar Paolo Abeni Committed by Greg Kroah-Hartman
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ipv6: route: enforce RCU protection in ip6_route_check_nh_onlink() 



[ Upstream commit bf1dc8bad1d42287164d216d8efb51c5cd381b18 ]

We need a RCU critical section around rt6_info->from deference, and
proper annotation.

Fixes: 4ed591c8ab44 ("net/ipv6: Allow onlink routes to have a device mismatch if it is the default route")
Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
Reviewed-by: default avatarDavid Ahern <dsahern@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 96dd4ef3

net/ipv6/route.c

+5 −1
Original line number Diff line number Diff line
@@ -2808,20 +2808,24 @@ static int ip6_route_check_nh_onlink(struct net *net, 
	u32 tbid = l3mdev_fib_table(dev) ? : RT_TABLE_MAIN;

	const struct in6_addr *gw_addr = &cfg->fc_gateway;

	u32 flags = RTF_LOCAL | RTF_ANYCAST | RTF_REJECT;

	struct fib6_info *from;

	struct rt6_info *grt;

	int err;



	err = 0;

	grt = ip6_nh_lookup_table(net, cfg, gw_addr, tbid, 0);

	if (grt) {

		rcu_read_lock();

		from = rcu_dereference(grt->from);

		if (!grt->dst.error &&

		    /* ignore match if it is the default route */

		    grt->from && !ipv6_addr_any(&grt->from->fib6_dst.addr) &&

		    from && !ipv6_addr_any(&from->fib6_dst.addr) &&

		    (grt->rt6i_flags & flags || dev != grt->dst.dev)) {

			NL_SET_ERR_MSG(extack,

				       "Nexthop has invalid gateway or device mismatch");

			err = -EINVAL;

		}

		rcu_read_unlock();



		ip6_rt_put(grt);

	}