Re: [PATCH] netpoll: fix netpoll_send_udp() bugs

[David Miller <davem@davemloft.net>]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Wed, 13 Jun 2012 07:30:21 +0200

> From: Eric Dumazet <edumazet@google.com>
> 
> Bogdan Hamciuc diagnosed and fixed following bug in netpoll_send_udp() :
> 
> "skb->len += len;" instead of "skb_put(skb, len);"
> 
> Meaning that _if_ a network driver needs to call skb_realloc_headroom(),
> only packet headers would be copied, leaving garbage in the payload.
> 
> However the skb_realloc_headroom() must be avoided as much as possible
> since it requires memory and netpoll tries hard to work even if memory
> is exhausted (using a pool of preallocated skbs)
> 
> It appears netpoll_send_udp() reserved 16 bytes for the ethernet header,
> which happens to work for typicall drivers but not all.
> 
> Right thing is to use LL_RESERVED_SPACE(dev)
> (And also add dev->needed_tailroom of tailroom)
> 
> This patch combines both fixes.
> 
> Many thanks to Bogdan for raising this issue.
> 
> Reported-by: Bogdan Hamciuc <bogdan.hamciuc@freescale.com>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Tested-by: Bogdan Hamciuc <bogdan.hamciuc@freescale.com>

Applied and queued up for -stable, thanks Eric.