skbuff: Fix skb checksum partial check.
Earlier patch6ae459bda
tried to detect void ckecksum partial skb by comparing pull length to checksum offset. But it does not work for all cases since checksum-offset depends on updates to skb->data. Following patch fixes it by validating checksum start offset after skb-data pointer is updated. Negative value of checksum offset start means there is no need to checksum. Fixes:6ae459bda
("skbuff: Fix skb checksum flag on skb pull") Reported-by: Andrew Vagin <avagin@odin.com> Signed-off-by: Pravin B Shelar <pshelar@nicira.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -2708,7 +2708,7 @@ static inline void skb_postpull_rcsum(struct sk_buff *skb,
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if (skb->ip_summed == CHECKSUM_COMPLETE)
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skb->csum = csum_sub(skb->csum, csum_partial(start, len, 0));
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else if (skb->ip_summed == CHECKSUM_PARTIAL &&
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skb_checksum_start_offset(skb) <= len)
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skb_checksum_start_offset(skb) < 0)
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skb->ip_summed = CHECKSUM_NONE;
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}
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@ -2958,11 +2958,12 @@ EXPORT_SYMBOL_GPL(skb_append_pagefrags);
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*/
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unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len)
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{
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unsigned char *data = skb->data;
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BUG_ON(len > skb->len);
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skb->len -= len;
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BUG_ON(skb->len < skb->data_len);
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skb_postpull_rcsum(skb, skb->data, len);
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return skb->data += len;
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__skb_pull(skb, len);
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skb_postpull_rcsum(skb, data, len);
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return skb->data;
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}
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EXPORT_SYMBOL_GPL(skb_pull_rcsum);
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