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Commit db43a282 authored by Octavian Purdila's avatar Octavian Purdila Committed by David S. Miller
Browse files

tcp: fix for splice receive when used with software LRO 



If an skb has nr_frags set to zero but its frag_list is not empty (as
it can happen if software LRO is enabled), and a previous
tcp_read_sock has consumed the linear part of the skb, then
__skb_splice_bits:

(a) incorrectly reports an error and

(b) forgets to update the offset to account for the linear part

Any of the two problems will cause the subsequent __skb_splice_bits
call (the one that handles the frag_list skbs) to either skip data,
or, if the unadjusted offset is greater then the size of the next skb
in the frag_list, make tcp_splice_read loop forever.

Signed-off-by: default avatarOctavian Purdila <opurdila@ixiacom.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 57413ebc

net/core/skbuff.c

+12 −5
Original line number Diff line number Diff line
@@ -1292,12 +1292,14 @@ static int __skb_splice_bits(struct sk_buff *skb, unsigned int *offset, 
{

	unsigned int nr_pages = spd->nr_pages;

	unsigned int poff, plen, len, toff, tlen;

	int headlen, seg;

	int headlen, seg, error = 0;



	toff = *offset;

	tlen = *total_len;

	if (!tlen)

	if (!tlen) {

		error = 1;

		goto err;

	}



	/*

	 * if the offset is greater than the linear part, go directly to
@@ -1339,7 +1341,8 @@ static int __skb_splice_bits(struct sk_buff *skb, unsigned int *offset, 
		 * just jump directly to update and return, no point

		 * in going over fragments when the output is full.

		 */

		if (spd_fill_page(spd, virt_to_page(p), plen, poff, skb))

		error = spd_fill_page(spd, virt_to_page(p), plen, poff, skb);

		if (error)

			goto done;



		tlen -= plen;
@@ -1369,7 +1372,8 @@ static int __skb_splice_bits(struct sk_buff *skb, unsigned int *offset, 
		if (!plen)

			break;



		if (spd_fill_page(spd, f->page, plen, poff, skb))

		error = spd_fill_page(spd, f->page, plen, poff, skb);

		if (error)

			break;



		tlen -= plen;
@@ -1382,7 +1386,10 @@ static int __skb_splice_bits(struct sk_buff *skb, unsigned int *offset, 
		return 0;

	}

err:

	return 1;

	/* update the offset to reflect the linear part skip, if any */

	if (!error)

		*offset = toff;

	return error;

}



/*