devlink: fix potential memort leak

We must free allocated skb when genlmsg_put() return fails.

Fixes: 1555d204e7 ("devlink: Support for pipeline debug (dpipe)")
Signed-off-by: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/devlink.c

@@ -1680,8 +1680,10 @@ start_again:
 
 	hdr = genlmsg_put(skb, info->snd_portid, info->snd_seq,
 			  &devlink_nl_family, NLM_F_MULTI, cmd);
-	if (!hdr)
+	if (!hdr) {
+		nlmsg_free(skb);
 		return -EMSGSIZE;
+	}
 
 	if (devlink_nl_put_handle(skb, devlink))
 		goto nla_put_failure;
@@ -2098,8 +2100,10 @@ start_again:
 
 	hdr = genlmsg_put(skb, info->snd_portid, info->snd_seq,
 			  &devlink_nl_family, NLM_F_MULTI, cmd);
-	if (!hdr)
+	if (!hdr) {
+		nlmsg_free(skb);
 		return -EMSGSIZE;
+	}
 
 	if (devlink_nl_put_handle(skb, devlink))
 		goto nla_put_failure;