linux-kernel - [109/151] ip_fragment: also adjust skb->truesize for packets not owned by a socket

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Date:	Wed, 16 Dec 2009 19:56:46 -0800
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Patrick McHardy <kaber@...sh.net>,
	"David S. Miller" <davem@...emloft.net>
Subject: [109/151] ip_fragment: also adjust skb->truesize for packets not owned by a socket

2.6.32-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Patrick McHardy <kaber@...sh.net>

[ Upstream commit b2722b1c3a893ec6021508da15b32282ec79f4da ]

When a large packet gets reassembled by ip_defrag(), the head skb
accounts for all the fragments in skb->truesize. If this packet is
refragmented again, skb->truesize is not re-adjusted to reflect only
the head size since its not owned by a socket. If the head fragment
then gets recycled and reused for another received fragment, it might
exceed the defragmentation limits due to its large truesize value.

skb_recycle_check() explicitly checks for linear skbs, so any recycled
skb should reflect its true size in skb->truesize. Change ip_fragment()
to also adjust the truesize value of skbs not owned by a socket.

Reported-and-tested-by: Ben Menchaca <ben@...footnetworks.com>
Signed-off-by: Patrick McHardy <kaber@...sh.net>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
---
 net/ipv4/ip_output.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -501,8 +501,8 @@ int ip_fragment(struct sk_buff *skb, int
 			if (skb->sk) {
 				frag->sk = skb->sk;
 				frag->destructor = sock_wfree;
-				truesizes += frag->truesize;
 			}
+			truesizes += frag->truesize;
 		}

 		/* Everything is OK. Generate! */

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