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Re: Memory leak in 2.6.11-rc1?

To: Russell King <rmk+lkml@xxxxxxxxxxxxxxxx>
Subject: Re: Memory leak in 2.6.11-rc1?
From: Patrick McHardy <kaber@xxxxxxxxx>
Date: Sun, 30 Jan 2005 18:58:27 +0100
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>, Robert.Olsson@xxxxxxxxxxx, akpm@xxxxxxxx, torvalds@xxxxxxxx, alexn@xxxxxxxxx, kas@xxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, netdev@xxxxxxxxxxx
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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;
 
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