[PATCH 1/1] openvswitch: check return value of nla_nest_start

From: Pan Bian
Date: Sun Apr 23 2017 - 02:44:07 EST


Function nla_nest_start() will return a NULL pointer on error, and its
return value should be validated before it is used. However, in function
queue_userspace_packet(), its return value is ignored. This may result
in NULL dereference when calling nla_nest_end(). This patch fixes the
bug.

Signed-off-by: Pan Bian <bianpan2016@xxxxxxx>
---
net/openvswitch/datapath.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index 9c62b63..34c0fbd 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -489,7 +489,8 @@ static int queue_userspace_packet(struct datapath *dp, struct sk_buff *skb,
err = ovs_nla_put_tunnel_info(user_skb,
upcall_info->egress_tun_info);
BUG_ON(err);
- nla_nest_end(user_skb, nla);
+ if (nla)
+ nla_nest_end(user_skb, nla);
}

if (upcall_info->actions_len) {
@@ -497,7 +498,7 @@ static int queue_userspace_packet(struct datapath *dp, struct sk_buff *skb,
err = ovs_nla_put_actions(upcall_info->actions,
upcall_info->actions_len,
user_skb);
- if (!err)
+ if (!err && nla)
nla_nest_end(user_skb, nla);
else
nla_nest_cancel(user_skb, nla);
--
1.9.1