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

Greg KH
2009-12-17T04:20:34Z

From: Patrick McHardy <kaber@trash.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@bigfootnetworks.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.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! */