2017-04-23 06:43:52

by Pan Bian

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

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 <[email protected]>
---
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

2017-04-23 20:23:09

by Pravin Shelar

Subject: Re: [ovs-dev] [PATCH 1/1] openvswitch: check return value of nla_nest_start

On Sat, Apr 22, 2017 at 11:43 PM, Pan Bian <[email protected]> wrote:
> 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 <[email protected]>
> ---
> 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);
There is enough memory allocated for the netlink message accounting
for all attributes beforehand. So it is not required to check retuned
'nla' after each attributes addition to the msg.


> }
>
> 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
>
>
> _______________________________________________
> dev mailing list
> [email protected]
> https://mail.openvswitch.org/mailman/listinfo/ovs-dev