geneve: should not call rt6_lookup() when ipv6 was disabled

liuhangbin · davem330 · commit c0a47e44c098 · 2019-02-07T10:48:42.000-08:00
When we add a new GENEVE device with IPv6 remote, checking only for IS_ENABLED(CONFIG_IPV6) is not enough as we may disable IPv6 in the kernel command line (ipv6.disable=1), and calling rt6_lookup() would cause a NULL pointer dereference. v2: - don't mix declarations and code (reported by Stefano Brivio, Eric Dumazet) - there's no need to use in6_dev_get() as we only need to check that idev exists (reported by David Ahern). This is under RTNL, so we can simply use __in6_dev_get() instead (Stefano, Eric). Reported-by: Jianlin Shi <jishi@redhat.com> Fixes: c40e89f ("geneve: configure MTU based on a lower device") Cc: Alexey Kodanev <alexey.kodanev@oracle.com> Signed-off-by: Hangbin Liu <liuhangbin@gmail.com> Reviewed-by: Stefano Brivio <sbrivio@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c
@@ -1512,9 +1512,13 @@ static void geneve_link_config(struct net_device *dev,
 	}
 #if IS_ENABLED(CONFIG_IPV6)
 	case AF_INET6: {
-		struct rt6_info *rt = rt6_lookup(geneve->net,
-						 &info->key.u.ipv6.dst, NULL, 0,
-						 NULL, 0);
+		struct rt6_info *rt;
+
+		if (!__in6_dev_get(dev))
+			break;
+
+		rt = rt6_lookup(geneve->net, &info->key.u.ipv6.dst, NULL, 0,
+				NULL, 0);
 
 		if (rt && rt->dst.dev)
 			ldev_mtu = rt->dst.dev->mtu - GENEVE_IPV6_HLEN;
