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[INET]: Prevent out-of-sync truesize on ip_fragment slow path

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When ip_fragment has to hit the slow path the value of skb->truesize
may go out of sync because we would have updated it without changing
the packet length.  This violates the constraints on truesize.

This patch postpones the update of skb->truesize to prevent this.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Herbert Xu
2008-01-28 20:45:20 -08:00
committed by David S. Miller
parent 1987e7b485
commit 29ffe1a5c5
2 changed files with 6 additions and 2 deletions
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4
net/ipv4/ip_output.c
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@@ -476,6 +476,7 @@ int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff*))
if (skb_shinfo(skb)->frag_list) {
struct sk_buff *frag;
int first_len = skb_pagelen(skb);
int truesizes = 0;
if (first_len - hlen > mtu ||
((first_len - hlen) & 7) ||
@@ -499,7 +500,7 @@ int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff*))
sock_hold(skb->sk);
frag->sk = skb->sk;
frag->destructor = sock_wfree;
skb->truesize -= frag->truesize;
truesizes += frag->truesize;
}
}
@@ -510,6 +511,7 @@ int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff*))
frag = skb_shinfo(skb)->frag_list;
skb_shinfo(skb)->frag_list = NULL;
skb->data_len = first_len - skb_headlen(skb);
skb->truesize -= truesizes;
skb->len = first_len;
iph->tot_len = htons(first_len);
iph->frag_off = htons(IP_MF);