[ 58/61] tcp: fix splice() and tcp collapsing interaction

Greg Kroah-Hartman
2013-02-12T20:36:32Z

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit f26845b43c75d3f32f98d194c1327b5b1e6b3fb0 ]

Under unusual circumstances, TCP collapse can split a big GRO TCP packet
while its being used in a splice(socket->pipe) operation.

skb_splice_bits() releases the socket lock before calling
splice_to_pipe().

[ 1081.353685] WARNING: at net/ipv4/tcp.c:1330 tcp_cleanup_rbuf+0x4d/0xfc()
[ 1081.371956] Hardware name: System x3690 X5 -[7148Z68]-
[ 1081.391820] cleanup rbuf bug: copied AD3BCF1 seq AD370AF rcvnxt AD3CF13

To fix this problem, we must eat skbs in tcp_recv_skb().

Remove the inline keyword from tcp_recv_skb() definition since
it has three call sites.

Reported-by: Christian Becker <c.becker@traviangames.com>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Tested-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv4/tcp.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)

--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1427,12 +1427,12 @@ static void tcp_service_net_dma(struct s
}
#endif

-static inline struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off)
+static struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off)
{
struct sk_buff *skb;
u32 offset;

- skb_queue_walk(&sk->sk_receive_queue, skb) {
+ while ((skb = skb_peek(&sk->sk_receive_queue)) != NULL) {
offset = seq - TCP_SKB_CB(skb)->seq;
if (tcp_hdr(skb)->syn)
offset--;
@@ -1440,6 +1440,11 @@ static inline struct sk_buff *tcp_recv_s
*off = offset;
return skb;
}
+ /* This looks weird, but this can happen if TCP collapsing
+ * splitted a fat GRO packet, while we released socket lock
+ * in skb_splice_bits()
+ */
+ sk_eat_skb(sk, skb, false);
}
return NULL;
}
@@ -1519,8 +1524,10 @@ int tcp_read_sock(struct sock *sk, read_
tcp_rcv_space_adjust(sk);

/* Clean up data we have read: This will do ACK frames. */
- if (copied > 0)
+ if (copied > 0) {
+ tcp_recv_skb(sk, seq, &offset);
tcp_cleanup_rbuf(sk, copied);
+ }
return copied;
}
EXPORT_SYMBOL(tcp_read_sock);