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authorEric Dumazet <edumazet@google.com>2015-06-16 07:59:11 -0700
committerDavid S. Miller <davem@davemloft.net>2015-06-21 09:23:22 -0700
commitf98f4514d07871da7a113dd9e3e330743fd70ae4 (patch)
treee48bffea6f290c61844781b165409cbc36b2f4e9
parent2dab80a8b486f02222a69daca6859519e05781d9 (diff)
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 95ec3eb417115fb ("packet: Add 'cpu' fanout policy.") Fixes: dc99f600698dc ("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>
-rw-r--r--net/packet/af_packet.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index b5989c6ee551..131545a06f05 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -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;