[PATCH 3.10 05/85] net-tcp: fastopen: fix high order allocations

Greg Kroah-Hartman
2014-03-21T00:45:31Z

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit f5ddcbbb40aa0ba7fbfe22355d287603dbeeaaac ]

This patch fixes two bugs in fastopen :

1) The tcp_sendmsg(..., @size) argument was ignored.

Code was relying on user not fooling the kernel with iovec mismatches

2) When MTU is about 64KB, tcp_send_syn_data() attempts order-5
allocations, which are likely to fail when memory gets fragmented.

Fixes: 783237e8daf13 ("net-tcp: Fast Open client - sending SYN-data")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Tested-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/net/tcp.h | 3 ++-
net/ipv4/tcp.c | 8 +++++---
net/ipv4/tcp_output.c | 7 ++++++-
3 files changed, 13 insertions(+), 5 deletions(-)

--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1308,7 +1308,8 @@ struct tcp_fastopen_request {
/* Fast Open cookie. Size 0 means a cookie request */
struct tcp_fastopen_cookie cookie;
struct msghdr *data; /* data in MSG_FASTOPEN */
- u16 copied; /* queued in tcp_connect() */
+ size_t size;
+ int copied; /* queued in tcp_connect() */
};
void tcp_free_fastopen_req(struct tcp_sock *tp);

--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1001,7 +1001,8 @@ void tcp_free_fastopen_req(struct tcp_so
}
}

-static int tcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg, int *size)
+static int tcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg,
+ int *copied, size_t size)
{
struct tcp_sock *tp = tcp_sk(sk);
int err, flags;
@@ -1016,11 +1017,12 @@ static int tcp_sendmsg_fastopen(struct s
if (unlikely(tp->fastopen_req == NULL))
return -ENOBUFS;
tp->fastopen_req->data = msg;
+ tp->fastopen_req->size = size;

flags = (msg->msg_flags & MSG_DONTWAIT) ? O_NONBLOCK : 0;
err = __inet_stream_connect(sk->sk_socket, msg->msg_name,
msg->msg_namelen, flags);
- *size = tp->fastopen_req->copied;
+ *copied = tp->fastopen_req->copied;
tcp_free_fastopen_req(tp);
return err;
}
@@ -1040,7 +1042,7 @@ int tcp_sendmsg(struct kiocb *iocb, stru

flags = msg->msg_flags;
if (flags & MSG_FASTOPEN) {
- err = tcp_sendmsg_fastopen(sk, msg, &copied_syn);
+ err = tcp_sendmsg_fastopen(sk, msg, &copied_syn, size);
if (err == -EINPROGRESS && copied_syn > 0)
goto out;
else if (err)
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2892,7 +2892,12 @@ static int tcp_send_syn_data(struct sock
space = __tcp_mtu_to_mss(sk, inet_csk(sk)->icsk_pmtu_cookie) -
MAX_TCP_OPTION_SPACE;

- syn_data = skb_copy_expand(syn, skb_headroom(syn), space,
+ space = min_t(size_t, space, fo->size);
+
+ /* limit to order-0 allocations */
+ space = min_t(size_t, space, SKB_MAX_HEAD(MAX_TCP_HEADER));
+
+ syn_data = skb_copy_expand(syn, MAX_TCP_HEADER, space,
sk->sk_allocation);
if (syn_data == NULL)
goto fallback;