From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: [PATCH] netpoll: fix netpoll_send_udp() bugs Date: Wed, 13 Jun 2012 07:30:21 +0200 Message-ID: <1339565421.22704.310.camel@edumazet-glaptop> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: netdev , Bogdan Hamciuc , Herbert Xu , Neil Horman To: David Miller Return-path: Received: from mail-ey0-f174.google.com ([209.85.215.174]:42247 "EHLO mail-ey0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752036Ab2FMFaY (ORCPT ); Wed, 13 Jun 2012 01:30:24 -0400 Received: by eaak11 with SMTP id k11so38217eaa.19 for ; Tue, 12 Jun 2012 22:30:23 -0700 (PDT) Sender: netdev-owner@vger.kernel.org List-ID: From: Eric Dumazet 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 Signed-off-by: Eric Dumazet Tested-by: Bogdan Hamciuc Cc: Herbert Xu Cc: Neil Horman --- net/core/netpoll.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/net/core/netpoll.c b/net/core/netpoll.c index 3d84fb9..f9f40b9 100644 --- a/net/core/netpoll.c +++ b/net/core/netpoll.c @@ -362,22 +362,23 @@ EXPORT_SYMBOL(netpoll_send_skb_on_dev); void netpoll_send_udp(struct netpoll *np, const char *msg, int len) { - int total_len, eth_len, ip_len, udp_len; + int total_len, ip_len, udp_len; struct sk_buff *skb; struct udphdr *udph; struct iphdr *iph; struct ethhdr *eth; udp_len = len + sizeof(*udph); - ip_len = eth_len = udp_len + sizeof(*iph); - total_len = eth_len + ETH_HLEN + NET_IP_ALIGN; + ip_len = udp_len + sizeof(*iph); + total_len = ip_len + LL_RESERVED_SPACE(np->dev); - skb = find_skb(np, total_len, total_len - len); + skb = find_skb(np, total_len + np->dev->needed_tailroom, + total_len - len); if (!skb) return; skb_copy_to_linear_data(skb, msg, len); - skb->len += len; + skb_put(skb, len); skb_push(skb, sizeof(*udph)); skb_reset_transport_header(skb);