[SKBUFF]: Fix up csum_start when head room changes

Thanks for noticing the bug where csum_start is not updated
when the head room changes.

This patch fixes that.  It also moves the csum/ip_summed
copying into copy_skb_header so that skb_copy_expand gets
it too.  I've checked its callers and no one should be upset
by this.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 10 deletions

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 35021eb3ed07..944189d96323 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -472,6 +472,9 @@ static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
 #ifdef CONFIG_INET
         new->sp         = secpath_get(old->sp);
 #endif
+        new->csum_start = old->csum_start;
+        new->csum_offset = old->csum_offset;
+        new->ip_summed = old->ip_summed;
         new->transport_header = old->transport_header;
         new->network_header   = old->network_header;
         new->mac_header       = old->mac_header;
@@ -545,8 +548,6 @@ struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask)
         skb_reserve(n, headerlen);
         /* Set the tail pointer and length */
         skb_put(n, skb->len);
-        n->csum      = skb->csum;
-        n->ip_summed = skb->ip_summed;
 
         if (skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len))
                 BUG();
@@ -589,8 +590,6 @@ struct sk_buff *pskb_copy(struct sk_buff *skb, gfp_t gfp_mask)
         skb_put(n, skb_headlen(skb));
         /* Copy the bytes */
         skb_copy_from_linear_data(skb, n->data, n->len);
-        n->csum      = skb->csum;
-        n->ip_summed = skb->ip_summed;
 
         n->truesize += skb->data_len;
         n->data_len  = skb->data_len;
@@ -686,6 +685,7 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
         skb->transport_header += off;
         skb->network_header   += off;
         skb->mac_header       += off;
+        skb->csum_start       += off;
         skb->cloned   = 0;
         skb->hdr_len  = 0;
         skb->nohdr    = 0;
@@ -734,9 +734,6 @@ struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom)
  *
  *      You must pass %GFP_ATOMIC as the allocation priority if this function
  *      is called from an interrupt.
- *
- *      BUG ALERT: ip_summed is not copied. Why does this work? Is it used
- *      only by netfilter in the cases when checksum is recalculated? --ANK
  */
 struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
                                 int newheadroom, int newtailroom,
@@ -749,7 +746,7 @@ struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
                                       gfp_mask);
         int oldheadroom = skb_headroom(skb);
         int head_copy_len, head_copy_off;
-        int off = 0;
+        int off;
 
         if (!n)
                 return NULL;
@@ -773,12 +770,13 @@ struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
 
         copy_skb_header(n, skb);
 
-#ifdef NET_SKBUFF_DATA_USES_OFFSET
         off                  = newheadroom - oldheadroom;
-#endif
+        n->csum_start       += off;
+#ifdef NET_SKBUFF_DATA_USES_OFFSET
         n->transport_header += off;
         n->network_header   += off;
         n->mac_header       += off;
+#endif
 
         return n;
 }