On Mon, 2013-06-17 at 10:18 -0400, Jun Chen wrote:
> When search the first skb to collapse,the condition of overlap to the next
> one have been
> reached,but the start is less than TCP_SKB_CB(skb)->seq at this time, then
> followed process
> will trigger the BUG_ON of the offset(start - TCP_SKB_CB(skb)->seq).
> So this patch add one check (! before(start,TCP_SKB_CB(skb)->seq)) to avoid
> this ipanic.
>
> Signed-off-by: Chen Jun <jun.d.c...@intel.com>
> ---
> net/ipv4/tcp_input.c | 3 ++-
> 1 files changed, 2 insertions(+), 1 deletions(-)
>
> diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
> index 9c62257..4c745c5 100644
> --- a/net/ipv4/tcp_input.c
> +++ b/net/ipv4/tcp_input.c
> @@ -4465,7 +4465,8 @@ restart:
> * overlaps to the next one.
> */
> if (!tcp_hdr(skb)->syn && !tcp_hdr(skb)->fin &&
> - (tcp_win_from_space(skb->truesize) > skb->len ||
> + ((tcp_win_from_space(skb->truesize) > skb->len &&
> + !before(start, TCP_SKB_CB(skb)->seq)) ||
> before(TCP_SKB_CB(skb)->seq, start))) {
> end_of_skbs = false;
> break;
Hmm... I must say I do not understand this patch.
If we find a skb with before(TCP_SKB_CB(skb)->seq, start), then the
final condition will be true.
Let's rewrite your code to equivalent one :
if (!tcp_hdr(skb)->syn && !tcp_hdr(skb)->fin &&
(before(TCP_SKB_CB(skb)->seq, start) ||
tcp_win_from_space(skb->truesize) > skb->len)) {
So it seems your patch would not solve the problem for all
possible skbs (aka not bloated) ?
Please tell us how you trigger this bug, and send the stack trace.
Thanks
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