Subject: Re: Memory leak in 2.6.11-rc1?

From: Patrick McHardy <[email-masked]>
Date: Sun, 30 Jan 2005 18:58:27 +0100

Patrick McHardy wrote:

>> Russell King wrote:
>>
>>> I don't know if the code is using fragment lists in ip_fragment(), but
>>> on reading the code a question comes to mind: if we have a list of
>>> fragments, does each fragment skb have a valid (and refcounted) dst
>>> pointer before ip_fragment() does it's job?  If yes, then isn't the
>>> first ip_copy_metadata() in ip_fragment() going to overwrite this
>>> pointer without dropping the refcount?
>>>
>> Nice spotting. If conntrack isn't loaded defragmentation happens after
>> routing, so this is likely the cause.
>
>
> OTOH, if conntrack isn't loaded forwarded packet are never defragmented,
> so frag_list should be empty. So probably false alarm, sorry.

Ok, final decision: you are right :) conntrack also defragments locally
generated packets before they hit ip_fragment. In this case the fragments
have skb->dst set.

Regards
Patrick

===== net/ipv4/ip_output.c 1.74 vs edited =====
--- 1.74/net/ipv4/ip_output.c	2005-01-25 01:40:10 +01:00
+++ edited/net/ipv4/ip_output.c	2005-01-30 18:54:43 +01:00
@@ -389,6 +389,7 @@
 	to->priority = from->priority;
 	to->protocol = from->protocol;
 	to->security = from->security;
+	dst_release(to->dst);
 	to->dst = dst_clone(from->dst);
 	to->dev = from->dev;