From: Eric Dumazet <eduma...@google.com> [ Upstream commit f98f4514d07871da7a113dd9e3e330743fd70ae4 ]
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 95ec3eb417115fb ("packet: Add 'cpu' fanout policy.") Fixes: dc99f600698dc ("packet: Add fanout support.") Signed-off-by: Eric Dumazet <eduma...@google.com> Cc: Willem de Bruijn <will...@google.com> Signed-off-by: David S. Miller <da...@davemloft.net> Signed-off-by: Sasha Levin <sasha.le...@oracle.com> --- net/packet/af_packet.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 07c04a8..d465f9f 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -1336,7 +1336,7 @@ 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; -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html