[PATCH] openvswitch: add null pointer check on upcall

[Colin King]

From: Colin Ian King <colin.k...@canonical.com>

upcall may be assigned a NULL pointer as genlmsg_put can potentially
return a NULL.  Add a null check to avoid a null pointer dereference
on upcall.

Detected by CoverityScan, CID#728404 ("Dereference null return value")

Fixes: commit ccb1352e76cf ("net: Add Open vSwitch kernel components.")
Signed-off-by: Colin Ian King <colin.k...@canonical.com>
---
 net/openvswitch/datapath.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index 4d38ac044cee..e8fb3d76fa6e 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -461,6 +461,10 @@ static int queue_userspace_packet(struct datapath *dp, 
struct sk_buff *skb,
 
        upcall = genlmsg_put(user_skb, 0, 0, &dp_packet_genl_family,
                             0, upcall_info->cmd);
+       if (!upcall) {
+               err = -ENOBUFS;
+               goto out;
+       }
        upcall->dp_ifindex = dp_ifindex;
 
        err = ovs_nla_put_key(key, key, OVS_PACKET_ATTR_KEY, false, user_skb);
-- 
2.14.1