Commit f98f4514 authored Jun 16, 2015 by Eric Dumazet Committed by David S. Miller Jun 21, 2015

packet: read num_members once in packet_rcv_fanout()



We need to tell compiler it must not read f->num_members multiple
times. Otherwise testing if num is not zero is flaky, and we could
attempt an invalid divide by 0 in fanout_demux_cpu()

Note bug was present in packet_rcv_fanout_hash() and
packet_rcv_fanout_lb() but final 3.1 had a simple location
after commit 95ec3eb4 ("packet: Add 'cpu' fanout policy.")

Fixes: dc99f600 ("packet: Add fanout support.")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 2dab80a8

net/packet/af_packet.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1353,7 +1353,7 @@ static int packet_rcv_fanout(struct sk_buff skb, struct net_device dev,
		struct packet_type pt, struct net_device orig_dev)
		{
		struct packet_fanout *f = pt->af_packet_priv;
		unsigned int num = f->num_members;
		unsigned int num = READ_ONCE(f->num_members);
		struct packet_sock *po;
		unsigned int idx;

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