4.3-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet <edumazet@xxxxxxxxxx>
[ Upstream commit 07e100f984975cb0417a7d5e626d0409efbad478 ]
Yuchung tracked a regression caused by commit 57be5bdad759 ("ip: convert
tcp_sendmsg() to iov_iter primitives") for TCP Fast Open.
Some Fast Open users do not actually add any data in the SYN packet.
Fixes: 57be5bdad759 ("ip: convert tcp_sendmsg() to iov_iter primitives")
Reported-by: Yuchung Cheng <ycheng@xxxxxxxxxx>
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Acked-by: Yuchung Cheng <ycheng@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv4/tcp_output.c | 23 ++++++++++++-----------
1 file changed, 12 insertions(+), 11 deletions(-)
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -3147,7 +3147,7 @@ static int tcp_send_syn_data(struct sock
{
struct tcp_sock *tp = tcp_sk(sk);
struct tcp_fastopen_request *fo = tp->fastopen_req;
- int syn_loss = 0, space, err = 0, copied;
+ int syn_loss = 0, space, err = 0;
unsigned long last_syn_loss = 0;
struct sk_buff *syn_data;
@@ -3185,17 +3185,18 @@ static int tcp_send_syn_data(struct sock
goto fallback;
syn_data->ip_summed = CHECKSUM_PARTIAL;
memcpy(syn_data->cb, syn->cb, sizeof(syn->cb));
- copied = copy_from_iter(skb_put(syn_data, space), space,
- &fo->data->msg_iter);
- if (unlikely(!copied)) {
- kfree_skb(syn_data);
- goto fallback;
- }
- if (copied != space) {
- skb_trim(syn_data, copied);
- space = copied;
+ if (space) {
+ int copied = copy_from_iter(skb_put(syn_data, space), space,
+ &fo->data->msg_iter);
+ if (unlikely(!copied)) {
+ kfree_skb(syn_data);
+ goto fallback;
+ }
+ if (copied != space) {
+ skb_trim(syn_data, copied);
+ space = copied;
+ }
}
-
/* No more data pending in inet_wait_for_connect() */
if (space == fo->size)
fo->data = NULL;
--
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