From 9207f9d45b0ad071baa128e846d7e7ed85016df3 Mon Sep 17 00:00:00 2001 From: Konstantin Khlebnikov Date: Fri, 8 Jan 2016 15:21:46 +0300 Subject: net: preserve IP control block during GSO segmentation Skb_gso_segment() uses skb control block during segmentation. This patch adds 32-bytes room for previous control block which will be copied into all resulting segments. This patch fixes kernel crash during fragmenting forwarded packets. Fragmentation requires valid IP CB in skb for clearing ip options. Also patch removes custom save/restore in ovs code, now it's redundant. Signed-off-by: Konstantin Khlebnikov Link: http://lkml.kernel.org/r/CALYGNiP-0MZ-FExV2HutTvE9U-QQtkKSoE--KN=JQE5STYsjAA@mail.gmail.com Signed-off-by: David S. Miller --- net/core/dev.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'net/core') diff --git a/net/core/dev.c b/net/core/dev.c index 0ca95d5d7af0..cc9e3652cf93 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -2695,6 +2695,8 @@ static inline bool skb_needs_check(struct sk_buff *skb, bool tx_path) * * It may return NULL if the skb requires no segmentation. This is * only possible when GSO is used for verifying header integrity. + * + * Segmentation preserves SKB_SGO_CB_OFFSET bytes of previous skb cb. */ struct sk_buff *__skb_gso_segment(struct sk_buff *skb, netdev_features_t features, bool tx_path) @@ -2709,6 +2711,9 @@ struct sk_buff *__skb_gso_segment(struct sk_buff *skb, return ERR_PTR(err); } + BUILD_BUG_ON(SKB_SGO_CB_OFFSET + + sizeof(*SKB_GSO_CB(skb)) > sizeof(skb->cb)); + SKB_GSO_CB(skb)->mac_offset = skb_headroom(skb); SKB_GSO_CB(skb)->encap_level = 0; -- cgit v1.2.3