skbuff: Fix skb checksum partial check. (31b33dfb) · Commits · 戴 / test

Earlier patch 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: ("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>

include/linux/skbuff.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -2708,7 +2708,7 @@ static inline void skb_postpull_rcsum(struct sk_buff *skb,
		if (skb->ip_summed == CHECKSUM_COMPLETE)
		skb->csum = csum_sub(skb->csum, csum_partial(start, len, 0));
		else if (skb->ip_summed == CHECKSUM_PARTIAL &&
		skb_checksum_start_offset(skb) <= len)
		skb_checksum_start_offset(skb) < 0)
		skb->ip_summed = CHECKSUM_NONE;
		}

net/core/skbuff.c

+5 −4

Original line number	Diff line number	Diff line
		@@ -2958,11 +2958,12 @@ EXPORT_SYMBOL_GPL(skb_append_pagefrags);
		*/
		unsigned char skb_pull_rcsum(struct sk_buff skb, unsigned int len)
		{
		unsigned char *data = skb->data;

		BUG_ON(len > skb->len);
		skb->len -= len;
		BUG_ON(skb->len < skb->data_len);
		skb_postpull_rcsum(skb, skb->data, len);
		return skb->data += len;
		__skb_pull(skb, len);
		skb_postpull_rcsum(skb, data, len);
		return skb->data;
		}
		EXPORT_SYMBOL_GPL(skb_pull_rcsum);

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