Messages in this thread Patch in this message | | | Subject | Re: Regression, bisected: reference leak with IPSec since ~2.6.31 | From | Eric Dumazet <> | Date | Tue, 21 Sep 2010 11:21:00 +0200 |
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Le mardi 21 septembre 2010 à 09:12 +0000, Jarek Poplawski a écrit : > On 2010-09-20 23:31, Eric Dumazet wrote: > ... > > [PATCH] ip : fix truesize mismatch in ip fragmentation > > > > We should not set frag->destructor to sock_wkfree() until we are sure we > > dont hit slow path in ip_fragment(). Or we risk uncharging > > frag->truesize twice, and in the end, having negative socket > > sk_wmem_alloc counter, or even freeing socket sooner than expected. > > > > Many thanks to Nick Bowler, who provided a very clean bug report and > > test programs. > > > > While Nick bisection pointed to commit 2b85a34e911bf483 (net: No more > > expensive sock_hold()/sock_put() on each tx), underlying bug is older. > > > > Reported-and-bisected-by: Nick Bowler <nbowler@elliptictech.com> > > Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> > > --- > > net/ipv4/ip_output.c | 8 ++++---- > > net/ipv6/ip6_output.c | 10 +++++----- > > 2 files changed, 9 insertions(+), 9 deletions(-) > > > > diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c > > index 04b6989..126d9b3 100644 > > --- a/net/ipv4/ip_output.c > > +++ b/net/ipv4/ip_output.c > > @@ -490,7 +490,6 @@ int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)) > > if (skb_has_frags(skb)) { > > struct sk_buff *frag; > > int first_len = skb_pagelen(skb); > > - int truesizes = 0; > > > > if (first_len - hlen > mtu || > > ((first_len - hlen) & 7) || > > @@ -510,11 +509,13 @@ int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)) > > goto slow_path; > > > > BUG_ON(frag->sk); > > - if (skb->sk) { > > + } > > + if (skb->sk) { > > + skb_walk_frags(skb, frag) { > > frag->sk = skb->sk; > > frag->destructor = sock_wfree; > > Nice catch, but it seems doing it in the first loop as now, and > reverting changes before goto slow_path might be more optimal here. >
I thought of this, but found this function already very complex.
Once everything is in cpu caches, the added loop is very cheap.
I liked the :
<check everything without changing state> if something wrong goto slow_path else <OK, lets do destructive things>
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