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-rw-r--r--net/core/dev.c21
1 files changed, 10 insertions, 11 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index 39aba4862f21..38b03da5c1ca 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1362,22 +1362,21 @@ int skb_checksum_help(struct sk_buff *skb)
goto out_set_summed;
}
- if (skb_cloned(skb)) {
+ offset = skb->csum_start - skb_headroom(skb);
+ BUG_ON(offset >= skb_headlen(skb));
+ csum = skb_checksum(skb, offset, skb->len - offset, 0);
+
+ offset += skb->csum_offset;
+ BUG_ON(offset + sizeof(__sum16) > skb_headlen(skb));
+
+ if (skb_cloned(skb) &&
+ !skb_clone_writable(skb, offset + sizeof(__sum16))) {
ret = pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
if (ret)
goto out;
}
- offset = skb->csum_start - skb_headroom(skb);
- BUG_ON(offset > (int)skb->len);
- csum = skb_checksum(skb, offset, skb->len-offset, 0);
-
- offset = skb_headlen(skb) - offset;
- BUG_ON(offset <= 0);
- BUG_ON(skb->csum_offset + 2 > offset);
-
- *(__sum16 *)(skb->head + skb->csum_start + skb->csum_offset) =
- csum_fold(csum);
+ *(__sum16 *)(skb->data + offset) = csum_fold(csum);
out_set_summed:
skb->ip_summed = CHECKSUM_NONE;
out: