Subject: [RFC] Move in6_dev_hold under CONFIG_IPV6_PRIVACY

From: David Marchand <[email-masked]>
Date: Thu, 30 Aug 2012 11:42:33 +0200

Hello,

I am currently looking at a problem with in6 interface refcnt on a 
really old kernel and I have just noticed something I find suspicious in 
all kernels until now.

The comment at net/ipv6/addrconf.c:396 suggests that the call to 
in6_dev_hold is only for ipv6_regen_rndid.
As a consequence, if CONFIG_IPV6_PRIVACY is not set, then this 
in6_dev_hold will leak a refcnt.

Can someone look at this ?
I did not test this patch, yet it looks reasonable to me.

Thank you.

$ git diff
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 6bc85f7..263fcf3 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -393,11 +393,6 @@ static struct inet6_dev *ipv6_add_dev(struct 
net_device *dev)
                 return NULL;
         }

-       /* One reference from device.  We must do this before
-        * we invoke __ipv6_regen_rndid().
-        */
-       in6_dev_hold(ndev);
-
         if (dev->flags & (IFF_NOARP | IFF_LOOPBACK))
                 ndev->cnf.accept_dad = -1;

@@ -410,6 +405,12 @@ static struct inet6_dev *ipv6_add_dev(struct 
net_device *dev)

  #ifdef CONFIG_IPV6_PRIVACY
         INIT_LIST_HEAD(&ndev->tempaddr_list);
+
+       /* One reference from device.  We must do this before
+        * we invoke ipv6_regen_rndid().
+        */
+       in6_dev_hold(ndev);
+
         setup_timer(&ndev->regen_timer, ipv6_regen_rndid, (unsigned 
long)ndev);
         if ((dev->flags&IFF_LOOPBACK) ||
             dev->type == ARPHRD_TUNNEL ||

-- 
David Marchand

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