From: Pravin B Shelar Date: Tue, 29 Sep 2015 00:24:25 +0000 (-0700) Subject: skbuff: Fix skb checksum partial check. X-Git-Tag: v3.16.35~1175 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=fc3befaacb2c900d239c65562f253b95344448b0;p=thirdparty%2Fkernel%2Fstable.git skbuff: Fix skb checksum partial check. commit 31b33dfb0a144469dd805514c9e63f4993729a48 upstream. 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 Signed-off-by: Pravin B Shelar Signed-off-by: David S. Miller Signed-off-by: Luis Henriques --- diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index cfe9676d2e718..010bc80be91c4 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -2439,7 +2439,7 @@ 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 167a92c896b9b..a280d04a34141 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -2869,11 +2869,12 @@ 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);