From 9fa5fdf291c9b58b1cb8b4bb2a0ee57efa21d635 Mon Sep 17 00:00:00 2001 From: Dimitris Michailidis <dm@chelsio.com> Date: Mon, 26 Jan 2009 22:15:31 -0800 Subject: [PATCH] tcp: Fix length tcp_splice_data_recv passes to skb_splice_bits. tcp_splice_data_recv has two lengths to consider: the len parameter it gets from tcp_read_sock, which specifies the amount of data in the skb, and rd_desc->count, which is the amount of data the splice caller still wants. Currently it passes just the latter to skb_splice_bits, which then splices min(rd_desc->count, skb->len - offset) bytes. Most of the time this is fine, except when the skb contains urgent data. In that case len goes only up to the urgent byte and is less than skb->len - offset. By ignoring len tcp_splice_data_recv may a) splice data tcp_read_sock told it not to, b) return to tcp_read_sock a value > len. Now, tcp_read_sock doesn't handle used > len and leaves the socket in a bad state (both sk_receive_queue and copied_seq are bad at that point) resulting in duplicated data and corruption. Fix by passing min(rd_desc->count, len) to skb_splice_bits. Signed-off-by: Dimitris Michailidis <dm@chelsio.com> Acked-by: Eric Dumazet <dada1@cosmosbay.com> Signed-off-by: David S. Miller <davem@davemloft.net> --- net/ipv4/tcp.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 0cd71b84e483d..76b148bcb0dcb 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -524,7 +524,8 @@ static int tcp_splice_data_recv(read_descriptor_t *rd_desc, struct sk_buff *skb, struct tcp_splice_state *tss = rd_desc->arg.data; int ret; - ret = skb_splice_bits(skb, offset, tss->pipe, rd_desc->count, tss->flags); + ret = skb_splice_bits(skb, offset, tss->pipe, min(rd_desc->count, len), + tss->flags); if (ret > 0) rd_desc->count -= ret; return ret; -- 2.30.2