On Thu, Sep 14, 2006 at 11:53:48PM +0300, Mika Penttil? wrote:
> Jon Mason wrote:
> >In br_dev_queue_push_xmit, why is the check to drop mtu oversized
> >packets not checking for enough room for the impending ETH_HLEN size
> >skb_push? In some code currently under development, we are seeing
> >skb_under_panic being called from the "skb_push(skb, ETH_HLEN)" in that
> >code. It seems to me it would be better to drop those skbs than panic.
> >Attached is a patch to do this.
> >
> >Thanks,
> >Jon
> >
> >Signed-off-by: Jon Mason <[EMAIL PROTECTED]>
> >
> >diff -r b1d36669f98d net/bridge/br_forward.c
> >--- a/net/bridge/br_forward.c Mon Sep 4 03:00:04 2006 +0000
> >+++ b/net/bridge/br_forward.c Thu Sep 14 13:18:04 2006 -0500
> >@@ -29,7 +29,8 @@ static inline int should_deliver(const s
> >
> > static inline unsigned packet_length(const struct sk_buff *skb)
> > {
> >- return skb->len - (skb->protocol == htons(ETH_P_8021Q) ? VLAN_HLEN :
> >0);
> >+ return skb->len - ETH_HLEN -
> >+ (skb->protocol == htons(ETH_P_8021Q) ? VLAN_HLEN : 0);
> > }
> >
> >
> packet_length() is a wrong place to do that, mtu has nothing to do with
> skb headroom.
Oops, you are 100% correct. So what would be the best way to handle
this, as a panic is pretty nasty? Wouldn't it be better to check the
packet to see if there is sufficient headroom, BUG, and then drop it
(or allocate a new packet with sufficient headroom and proceed with
the skb_push)?
Thanks,
Jon
>
> --Mika
>
>
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