From: Pravin B Shelar <pshelar@xxxxxxxxxx>
3.12-stable review patch. If anyone has any objections, please let me know.
===============
[ 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: Andrew Vagin <avagin@xxxxxxxx>
Signed-off-by: Pravin B Shelar <pshelar@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
include/linux/skbuff.h | 2 +-
net/core/skbuff.c | 9 +++++----
2 files changed, 6 insertions(+), 5 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 80fad984cd8e..16e753a9922a 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2265,7 +2265,7 @@ 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;
}
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index b01dd5f421da..de76393a9916 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2726,11 +2726,12 @@ 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);
--
2.6.2
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