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tcp: fix for splice receive when used with software LRO

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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: Octavian Purdila <opurdila@ixiacom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Octavian Purdila 2008-06-27 17:27:21 -07:00 committed by David S. Miller
parent 57413ebc4e
commit db43a282d3
1 changed files with 12 additions and 5 deletions
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17
net/core/skbuff.c
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@ -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 nr_pages = spd->nr_pages;
unsigned int poff, plen, len, toff, tlen; unsigned int poff, plen, len, toff, tlen;
int headlen, seg; int headlen, seg, error = 0;
toff = *offset; toff = *offset;
tlen = *total_len; tlen = *total_len;
if (!tlen) if (!tlen) {
error = 1;
goto err; goto err;
}
/* /*
* if the offset is greater than the linear part, go directly to * 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 * just jump directly to update and return, no point
* in going over fragments when the output is full. * 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; goto done;
tlen -= plen; tlen -= plen;
@ -1369,7 +1372,8 @@ static int __skb_splice_bits(struct sk_buff *skb, unsigned int *offset,
if (!plen) if (!plen)
break; break;
if (spd_fill_page(spd, f->page, plen, poff, skb)) error = spd_fill_page(spd, f->page, plen, poff, skb);
if (error)
break; break;
tlen -= plen; tlen -= plen;
@ -1382,7 +1386,10 @@ static int __skb_splice_bits(struct sk_buff *skb, unsigned int *offset,
return 0; return 0;
} }
err: err:
return 1; /* update the offset to reflect the linear part skip, if any */
if (!error)
*offset = toff;
return error;
} }
/* /*