Subject: Re: [PATCH v2] ipv6: fix incorrent ipv6 ipsec packet fragment

From: Steffen Klassert <[email-masked]>
Date: Tue, 20 Mar 2012 08:58:46 +0100

On Tue, Mar 20, 2012 at 11:22:59AM +0800, Gao feng wrote:
> Since commit 299b0767(ipv6: Fix IPsec slowpath fragmentation problem)
> In func ip6_append_data,after call skb_put(skb, fraglen + dst_exthdrlen)
> the skb->len contains dst_exthdrlen,and we don't reduce dst_exthdrlen at last
> This will make fraggap>0 in next "while cycle",and cause the size of skb incorrent
> 
> Fix this by reserve headroom for dst_exthdrlen.
> 
> Signed-off-by: Gao feng <[email-masked]>
> ---
>  net/ipv6/ip6_output.c |    8 +++++---
>  1 files changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
> index d97e071..8d5d204 100644
> --- a/net/ipv6/ip6_output.c
> +++ b/net/ipv6/ip6_output.c
> @@ -1418,6 +1418,8 @@ alloc_new_skb:
>  			skb->csum = 0;
>  			/* reserve for fragmentation */
>  			skb_reserve(skb, hh_len+sizeof(struct frag_hdr));
> +			/* reserve for ipsec header */
> +			skb_reserve(skb, dst_exthdrlen);

Why not 'reserve for fragmentation and ipsec header' instead
of calling skb_reserve() two times?

The rest of the patch looks good.