[PATCH net-next] lwtunnel: fix error path in lwtunnel_fill_encap()

Dan Carpenter
2017-04-28T13:03:48Z

We recently added a check to see if nla_nest_start() fails. There are
two issues with that. First, if it fails then I don't think we should
call nla_nest_cancel(). Second, it's slightly convoluted but the
current code returns success but we should return -EMSGSIZE instead.

Fixes: a50fe0ffd76f ("lwtunnel: check return value of nla_nest_start")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

diff --git a/net/core/lwtunnel.c b/net/core/lwtunnel.c
index 5cbed3816229..cfae3d5fe11f 100644
--- a/net/core/lwtunnel.c
+++ b/net/core/lwtunnel.c
@@ -203,7 +203,7 @@ int lwtunnel_fill_encap(struct sk_buff *skb, struct lwtunnel_state *lwtstate)
{
const struct lwtunnel_encap_ops *ops;
struct nlattr *nest;
- int ret = -EINVAL;
+ int ret;

if (!lwtstate)
return 0;
@@ -212,10 +212,11 @@ int lwtunnel_fill_encap(struct sk_buff *skb, struct lwtunnel_state *lwtstate)
lwtstate->type > LWTUNNEL_ENCAP_MAX)
return 0;

- ret = -EOPNOTSUPP;
nest = nla_nest_start(skb, RTA_ENCAP);
if (!nest)
- goto nla_put_failure;
+ return -EMSGSIZE;
+
+ ret = -EOPNOTSUPP;
rcu_read_lock();
ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
if (likely(ops && ops->fill_encap))