Patchwork netfilter: Correct calculation using skb->tail and skb-network_header

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Submitter Simon Horman
Date May 30, 2013, 11:55 p.m.
Message ID <1369958133-20576-1-git-send-email-horms@verge.net.au>
Download mbox | patch
Permalink /patch/247814/
State Superseded
Headers show

Comments

Simon Horman - May 30, 2013, 11:55 p.m.
This corrects an regression introduced by "net: Use 16bits for *_headers
fields of struct skbuff" when NET_SKBUFF_DATA_USES_OFFSET is not set. In
that case skb->tail will be a pointer whereas skb->network_header
will be an offset from head. This is corrected by using wrappers that
ensure that calculations are always made using pointers.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reported-by: Chen Gang <gang.chen@asianux.com>
Signed-off-by: Simon Horman <horms@verge.net.au>
---
 net/netfilter/nf_nat_helper.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
Simon Horman - May 30, 2013, 11:58 p.m.
On Fri, May 31, 2013 at 08:55:33AM +0900, Simon Horman wrote:
> This corrects an regression introduced by "net: Use 16bits for *_headers
> fields of struct skbuff" when NET_SKBUFF_DATA_USES_OFFSET is not set. In
> that case skb->tail will be a pointer whereas skb->network_header
> will be an offset from head. This is corrected by using wrappers that
> ensure that calculations are always made using pointers.

Sorry, I made this patch in a bit of a rush and I realise it it not
always correct as skb->tail is not always a pointer. I will re-spin the
patch.

> 
> Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
> Reported-by: Chen Gang <gang.chen@asianux.com>
> Signed-off-by: Simon Horman <horms@verge.net.au>
> ---
>  net/netfilter/nf_nat_helper.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/netfilter/nf_nat_helper.c b/net/netfilter/nf_nat_helper.c
> index 5fea563..fdbdfec 100644
> --- a/net/netfilter/nf_nat_helper.c
> +++ b/net/netfilter/nf_nat_helper.c
> @@ -104,7 +104,7 @@ static void mangle_contents(struct sk_buff *skb,
>  	/* move post-replacement */
>  	memmove(data + match_offset + rep_len,
>  		data + match_offset + match_len,
> -		skb->tail - (skb->network_header + dataoff +
> +		skb->tail - (skb_network_header(skb) + dataoff +
>  			     match_offset + match_len));
>  
>  	/* insert data from buffer */
> -- 
> 1.7.10.4
> 
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Patch

diff --git a/net/netfilter/nf_nat_helper.c b/net/netfilter/nf_nat_helper.c
index 5fea563..fdbdfec 100644
--- a/net/netfilter/nf_nat_helper.c
+++ b/net/netfilter/nf_nat_helper.c
@@ -104,7 +104,7 @@  static void mangle_contents(struct sk_buff *skb,
 	/* move post-replacement */
 	memmove(data + match_offset + rep_len,
 		data + match_offset + match_len,
-		skb->tail - (skb->network_header + dataoff +
+		skb->tail - (skb_network_header(skb) + dataoff +
 			     match_offset + match_len));
 
 	/* insert data from buffer */