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authorEric Dumazet <edumazet@google.com>2015-06-16 07:59:11 -0700
committerBen Hutchings <ben@decadent.org.uk>2015-08-07 00:32:17 +0100
commitf5a27902fd01ffc4b379101c64ac3a8cb69495bd (patch)
tree935f09648e1a52f8b239b884544161b96f2538c6 /net
parent41431e402fc405dcef9a468a815c68b322ad0e62 (diff)
packet: read num_members once in packet_rcv_fanout()
[ 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 <edumazet@google.com> Cc: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to '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 4f19bf248fcd..ca39a0c799f8 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1211,7 +1211,7 @@ 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 = ACCESS_ONCE(f->num_members);
struct packet_sock *po;
struct sock *sk;