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Commit f688246d authored by Pravin B Shelar's avatar Pravin B Shelar Committed by Sasha Levin
Browse files

skbuff: Fix skb checksum partial check. 



[ Upstream commit 31b33dfb0a144469dd805514c9e63f4993729a48 ]

Earlier patch 6ae459bda 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: default avatarAndrew Vagin <avagin@odin.com>
Signed-off-by: default avatarPravin B Shelar <pshelar@nicira.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
parent 6532c6b2

include/linux/skbuff.h

+1 −1
Original line number Diff line number Diff line
@@ -2550,7 +2550,7 @@ 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
@@ -2881,11 +2881,12 @@ EXPORT_SYMBOL(skb_append_datato_frags); 
 */

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);