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[NET]: Revert sk_buff walker cleanups.

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This reverts eefa390628

The simplification made in that change works with the assumption that
the 'offset' parameter to these functions is always positive or zero,
which is not true.  It can be and often is negative in order to access
SKB header values in front of skb->data.

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller
2007-04-27 15:21:23 -07:00
parent 50f732ee63
commit 1a028e5072
5 changed files with 158 additions and 86 deletions
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25
net/appletalk/ddp.c
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@ -937,11 +937,11 @@ static unsigned long atalk_sum_partial(const unsigned char *data,
static unsigned long atalk_sum_skb(const struct sk_buff *skb, int offset,
int len, unsigned long sum)
{
int end = skb_headlen(skb);
int start = skb_headlen(skb);
int i, copy;
/* checksum stuff in header space */
if ((copy = end - offset) > 0) {
if ( (copy = start - offset) > 0) {
if (copy > len)
copy = len;
sum = atalk_sum_partial(skb->data + offset, copy, sum);
@ -953,9 +953,11 @@ static unsigned long atalk_sum_skb(const struct sk_buff *skb, int offset,
/* checksum stuff in frags */
for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
BUG_TRAP(len >= 0);
int end;
end = offset + skb_shinfo(skb)->frags[i].size;
BUG_TRAP(start <= offset + len);
end = start + skb_shinfo(skb)->frags[i].size;
if ((copy = end - offset) > 0) {
u8 *vaddr;
skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
@ -963,31 +965,36 @@ static unsigned long atalk_sum_skb(const struct sk_buff *skb, int offset,
if (copy > len)
copy = len;
vaddr = kmap_skb_frag(frag);
sum = atalk_sum_partial(vaddr + frag->page_offset,
copy, sum);
sum = atalk_sum_partial(vaddr + frag->page_offset +
offset - start, copy, sum);
kunmap_skb_frag(vaddr);
if (!(len -= copy))
return sum;
offset += copy;
}
start = end;
}
if (skb_shinfo(skb)->frag_list) {
struct sk_buff *list = skb_shinfo(skb)->frag_list;
for (; list; list = list->next) {
BUG_TRAP(len >= 0);
int end;
end = offset + list->len;
BUG_TRAP(start <= offset + len);
end = start + list->len;
if ((copy = end - offset) > 0) {
if (copy > len)
copy = len;
sum = atalk_sum_skb(list, 0, copy, sum);
sum = atalk_sum_skb(list, offset - start,
copy, sum);
if ((len -= copy) == 0)
return sum;
offset += copy;
}
start = end;
}
}