netdev - [PATCH 2/2] openvswitch: Fix condition check in output_userspace() by using nla

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <1631867098-3891002-1-git-send-email-jiasheng@iscas.ac.cn>
Date:   Fri, 17 Sep 2021 08:24:58 +0000
From:   Jiasheng Jiang <jiasheng@...as.ac.cn>
To:     pshelar@....org, davem@...emloft.net, kuba@...nel.org
Cc:     netdev@...r.kernel.org, dev@...nvswitch.org,
        linux-kernel@...r.kernel.org, Jiasheng Jiang <jiasheng@...as.ac.cn>
Subject: [PATCH 2/2] openvswitch: Fix condition check in output_userspace() by using nla_ok()

Just using 'rem > 0' might be unsafe, so it's better
to use the nla_ok() instead.
Because we can see from the nla_next() that
'*remaining' might be smaller than 'totlen'. And nla_ok()
will avoid it happening.
For example, ovs_dp_process_packet() -> ovs_execute_actions()
-> do_execute_actions() -> output_userspace(), and attr comes
from OVS_CB(skb)->input_vport,which restores the received packet
from the user space.

Fixes: ccb1352e76cff0524e7ccb2074826a092dd13016
('net: Add Open vSwitch kernel components.')
Signed-off-by: Jiasheng Jiang <jiasheng@...as.ac.cn>
---
 net/openvswitch/actions.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index c23537f..e8236dd 100644
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -915,8 +915,7 @@ static int output_userspace(struct datapath *dp, struct sk_buff *skb,
 	upcall.cmd = OVS_PACKET_CMD_ACTION;
 	upcall.mru = OVS_CB(skb)->mru;
 
-	for (a = nla_data(attr), rem = nla_len(attr); rem > 0;
-	     a = nla_next(a, &rem)) {
+	nla_for_each_nested(a, attr, rem) {
 		switch (nla_type(a)) {
 		case OVS_USERSPACE_ATTR_USERDATA:
 			upcall.userdata = a;
-- 
2.7.4