[PATCH net 2/2] net-shapers: don't free reply skb after genlmsg_reply()

[Paul Moses <p@1g4.org>]

genlmsg_reply() hands the reply skb to netlink, and
netlink_unicast() consumes it on all return paths, whether the
skb is queued successfully or freed on an error path.

net_shaper_nl_get_doit() and net_shaper_nl_cap_get_doit()
currently jump to free_msg after genlmsg_reply() fails and call
nlmsg_free(msg), which can hit the same skb twice.

Return the genlmsg_reply() error directly and keep free_msg
only for pre-reply failures.

Fixes: 4b623f9f0f59 ("net-shapers: implement NL get operation")
Fixes: 553ea9f1efd6 ("net: shaper: implement introspection support")
Cc: stable@vger.kernel.org
Signed-off-by: Paul Moses <p@1g4.org>
---
 net/shaper/shaper.c | 11 ++---------
 1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/net/shaper/shaper.c b/net/shaper/shaper.c
index 3ad5a2d621a91..ab0de415546d6 100644
--- a/net/shaper/shaper.c
+++ b/net/shaper/shaper.c
@@ -760,11 +760,7 @@ int net_shaper_nl_get_doit(struct sk_buff *skb, struct genl_info *info)
 	if (ret)
 		goto free_msg;
 
-	ret = genlmsg_reply(msg, info);
-	if (ret)
-		goto free_msg;
-
-	return 0;
+	return genlmsg_reply(msg, info);
 
 free_msg:
 	nlmsg_free(msg);
@@ -1314,10 +1310,7 @@ int net_shaper_nl_cap_get_doit(struct sk_buff *skb, struct genl_info *info)
 	if (ret)
 		goto free_msg;
 
-	ret =  genlmsg_reply(msg, info);
-	if (ret)
-		goto free_msg;
-	return 0;
+	return genlmsg_reply(msg, info);
 
 free_msg:
 	nlmsg_free(msg);
-- 
2.53.GIT