Patch "packet: read num_members once in packet_rcv_fanout()" has been added to the 4.0-stable tree

This is a note to let you know that I've just added the patch titled

packet: read num_members once in packet_rcv_fanout()

to the 4.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
packet-read-num_members-once-in-packet_rcv_fanout.patch
and it can be found in the queue-4.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Eric Dumazet <[email protected]>
Date: Tue, 16 Jun 2015 07:59:11 -0700
Subject: packet: read num_members once in packet_rcv_fanout()

From: Eric Dumazet <[email protected]>

[ 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.")

---
 net/packet/af_packet.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -1347,7 +1347,7 @@ static int packet_rcv_fanout(struct sk_b
 			     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;
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.0/packet-avoid-out-of-bounds-read-in-round-robin-fanout.patch queue-4.0/net-don-t-wait-for-order-3-page-allocation.patch queue-4.0/tcp-do-not-call-tcp_fastopen_reset_cipher-from-interrupt-context.patch queue-4.0/packet-read-num_members-once-in-packet_rcv_fanout.patch queue-4.0/neigh-do-not-modify-unlinked-entries.patch queue-4.0/bnx2x-fix-lockdep-splat.patch