Subject: Re: [PATCH net-next 1/8] af_packet: Check return of dev_set_promiscuity/allmulti

From: Wang Chen <[email-masked]>
Date: Fri, 20 Jun 2008 10:41:24 +0800

Wang Chen said the following on 2008-6-20 10:13:
> David Miller said the following on 2008-6-20 10:05:
>> From: Wang Chen <[email-masked]>
>> Date: Fri, 20 Jun 2008 08:54:32 +0800
>>
>>> @@ -1245,7 +1247,8 @@ static int packet_mc_add(struct sock *sk, struct packet_mreq_max *mreq)
>>>  	i->count = 1;
>>>  	i->next = po->mclist;
>>>  	po->mclist = i;
>>> -	packet_dev_mc(dev, i, +1);
>>> +	/* Positive increment should be checked for overflow --WCN */
>>> +	err = packet_dev_mc(dev, i, 1);
>>>  
>> Please don't add these little signatures to comments.  That might have
>> been useful to do 10 years ago when we didn't use proper source
>> control, but now we do and anyone interested can do a "git blame"
>> to see who added that comment and why.
>>
>> Also, this comment doesn't really add any information.  We check
>> error return values simply because errors can happen, that's just
>> a straight fact.  If packet_dev_mc() and it's sub calls can error
>> for other reasons this comment is only telling part of the story
>> and as a result becomes inaccurate.
>>
>> Therefore, I'd like to ask that you not add this comment, it doesn't
>> really help anything.  This kind of information can go into the
>> commit log message.  That's where "why" information tends to belong.
>>

No useless comment :)

---
dev_set_promiscuity/allmulti might overflow.
Commit: "netdevice: Fix promiscuity and allmulti overflow" in net-next makes
dev_set_promiscuity/allmulti return error number if overflow happened.

In af_packet, we check all positive increment for promiscuity and allmulti
to get error return.

Signed-off-by: Wang Chen <[email-masked]>
---
 net/packet/af_packet.c |   10 ++++++----
 1 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 2cee87d..6370b9d 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1175,7 +1175,8 @@ static int packet_getname(struct socket *sock, struct sockaddr *uaddr,
 	return 0;
 }
 
-static void packet_dev_mc(struct net_device *dev, struct packet_mclist *i, int what)
+static int packet_dev_mc(struct net_device *dev, struct packet_mclist *i,
+			 int what)
 {
 	switch (i->type) {
 	case PACKET_MR_MULTICAST:
@@ -1185,13 +1186,14 @@ static void packet_dev_mc(struct net_device *dev, struct packet_mclist *i, int w
 			dev_mc_delete(dev, i->addr, i->alen, 0);
 		break;
 	case PACKET_MR_PROMISC:
-		dev_set_promiscuity(dev, what);
+		return dev_set_promiscuity(dev, what);
 		break;
 	case PACKET_MR_ALLMULTI:
-		dev_set_allmulti(dev, what);
+		return dev_set_allmulti(dev, what);
 		break;
 	default:;
 	}
+	return 0;
 }
 
 static void packet_dev_mclist(struct net_device *dev, struct packet_mclist *i, int what)
@@ -1245,7 +1247,7 @@ static int packet_mc_add(struct sock *sk, struct packet_mreq_max *mreq)
 	i->count = 1;
 	i->next = po->mclist;
 	po->mclist = i;
-	packet_dev_mc(dev, i, +1);
+	err = packet_dev_mc(dev, i, 1);
 
 done:
 	rtnl_unlock();
-- 
1.5.3.4