unix/dgram: peek beyond 0-sized skbs
"77c1090 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>
diff --git a/net/core/datagram.c b/net/core/datagram.c
index 368f9c3..99c4f52 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -187,7 +187,8 @@
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;
}