netdev - [PATCH net] ipv6: do not leave garbage in rt->fib6

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Message-Id: <20181005161750.179275-1-edumazet@google.com>
Date:   Fri,  5 Oct 2018 09:17:50 -0700
From:   Eric Dumazet <edumazet@...gle.com>
To:     "David S . Miller" <davem@...emloft.net>
Cc:     netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        David Ahern <dsahern@...il.com>
Subject: [PATCH net] ipv6: do not leave garbage in rt->fib6_metrics

In case ip_fib_metrics_init() returns an error, we better
rewrite rt->fib6_metrics with &dst_default_metrics so that
we do not crash later in ip_fib_metrics_put()

Fixes: 767a2217533f ("net: common metrics init helper for FIB entries")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Reported-by: syzbot <syzkaller@...glegroups.com>
---
 net/ipv6/route.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 6c1d817151cae45421dc976c5ea082b4115650be..74d97addf1af20dda0c2b6a2018e88696f9f7d5a 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2976,6 +2976,8 @@ static struct fib6_info *ip6_route_info_create(struct fib6_config *cfg,
 	rt->fib6_metrics = ip_fib_metrics_init(net, cfg->fc_mx, cfg->fc_mx_len);
 	if (IS_ERR(rt->fib6_metrics)) {
 		err = PTR_ERR(rt->fib6_metrics);
+		/* Do not leave garbage there. */
+		rt->fib6_metrics = (struct dst_metrics *)&dst_default_metrics;
 		goto out;
 	}
 
-- 
2.19.0.605.g01d371f741-goog