[PATCH net] ipv6: Fix __ip6_route_redirect

[Martin KaFai Lau <kafai@fb.com>]

In my last commit (a3c00e4: ipv6: Remove BACKTRACK macro), the changes in
__ip6_route_redirect is incorrect.  The following case is missed:
1. The for loop tries to find a valid gateway rt. If it fails to find
   one, rt will be NULL.
2. When rt is NULL, it is set to the ip6_null_entry.
3. The newly added 'else if', from a3c00e4, will stop the backtrack from
   happening.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
---
 net/ipv6/route.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 166e33b..49596535 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1242,12 +1242,16 @@ restart:
 		rt = net->ipv6.ip6_null_entry;
 	else if (rt->dst.error) {
 		rt = net->ipv6.ip6_null_entry;
-	} else if (rt == net->ipv6.ip6_null_entry) {
+		goto out;
+	}
+
+	if (rt == net->ipv6.ip6_null_entry) {
 		fn = fib6_backtrack(fn, &fl6->saddr);
 		if (fn)
 			goto restart;
 	}
 
+out:
 	dst_hold(&rt->dst);
 
 	read_unlock_bh(&table->tb6_lock);
-- 
1.8.1