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From:   Jiasheng Jiang <jiasheng@iscas.ac.cn>
To:     pshelar@ovn.org, davem@davemloft.net, kuba@kernel.org
Cc:     netdev@vger.kernel.org, dev@openvswitch.org,
        linux-kernel@vger.kernel.org, Jiasheng Jiang <jiasheng@iscas.ac.cn>
Subject: [PATCH] openvswitch: Fix condition check by using nla_ok()
Date:   Thu, 16 Sep 2021 01:48:36 +0000
Message-Id: <1631756916-3759083-1-git-send-email-jiasheng@iscas.ac.cn>
Precedence: bulk

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.

Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
---
 net/openvswitch/actions.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index 116e38a..8209ab1 100644
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -915,7 +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;
+	for (a = nla_data(attr), rem = nla_len(attr); nla_ok(a, rem);
 	     a = nla_next(a, &rem)) {
 		switch (nla_type(a)) {
 		case OVS_USERSPACE_ATTR_USERDATA:
-- 
2.7.4