Commit add05ad4 authored Apr 29, 2013 by Benjamin Poirier Committed by David S. Miller Apr 30, 2013

unix/dgram: peek beyond 0-sized skbs



"77c1090f net: fix infinite loop in __skb_recv_datagram()" (v3.8) introduced a
regression:
After that commit, recv can no longer peek beyond a 0-sized skb in the queue.
__skb_recv_datagram() instead stops at the first skb with len == 0 and results
in the system call failing with -EFAULT via skb_copy_datagram_iovec().

When peeking at an offset with 0-sized skb(s), each one of those is received
only once, in sequence. The offset starts moving forward again after receiving
datagrams with len > 0.

Signed-off-by: Benjamin Poirier <bpoirier@suse.de>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent e5195c1f

net/core/datagram.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -187,7 +187,8 @@ struct sk_buff __skb_recv_datagram(struct sock sk, unsigned int flags,
		skb_queue_walk(queue, skb) {
		*peeked = skb->peeked;
		if (flags & MSG_PEEK) {
		if (*off >= skb->len && skb->len) {
		if (off >= skb->len && (skb->len \|\| off \|\|
		skb->peeked)) {
		*off -= skb->len;
		continue;
		}