netdev - [PATCH net-next v3 2/2] mctp: Fix incorrect netdev unref for extended addr

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Date:   Tue, 22 Feb 2022 12:17:39 +0800
From:   Matt Johnston <matt@...econstruct.com.au>
To:     netdev@...r.kernel.org
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Jeremy Kerr <jk@...econstruct.com.au>
Subject: [PATCH net-next v3 2/2] mctp: Fix incorrect netdev unref for extended addr

In the extended addressing local route output codepath
dev_get_by_index_rcu() doesn't take a dev_hold() so we shouldn't
dev_put().

Signed-off-by: Matt Johnston <matt@...econstruct.com.au>
---
 net/mctp/route.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/net/mctp/route.c b/net/mctp/route.c
index 6f277e56b168..5078ce3315cf 100644
--- a/net/mctp/route.c
+++ b/net/mctp/route.c
@@ -838,7 +838,6 @@ int mctp_local_output(struct sock *sk, struct mctp_route *rt,
 	struct mctp_skb_cb *cb = mctp_cb(skb);
 	struct mctp_route tmp_rt = {0};
 	struct mctp_sk_key *key;
-	struct net_device *dev;
 	struct mctp_hdr *hdr;
 	unsigned long flags;
 	unsigned int mtu;
@@ -851,12 +850,12 @@ int mctp_local_output(struct sock *sk, struct mctp_route *rt,
 
 	if (rt) {
 		ext_rt = false;
-		dev = NULL;
-
 		if (WARN_ON(!rt->dev))
 			goto out_release;
 
 	} else if (cb->ifindex) {
+		struct net_device *dev;
+
 		ext_rt = true;
 		rt = &tmp_rt;
 
@@ -866,7 +865,6 @@ int mctp_local_output(struct sock *sk, struct mctp_route *rt,
 			rcu_read_unlock();
 			return rc;
 		}
-
 		rt->dev = __mctp_dev_get(dev);
 		rcu_read_unlock();
 
@@ -947,11 +945,9 @@ int mctp_local_output(struct sock *sk, struct mctp_route *rt,
 	if (!ext_rt)
 		mctp_route_release(rt);
 
-	dev_put(dev);
 	mctp_dev_put(tmp_rt.dev);
 
 	return rc;
-
 }
 
 /* route management */
-- 
2.32.0