Patch "packet: read num_members once in packet_rcv_fanout()" has been added to the 3.14-stable tree

[<gregkh@linuxfoundation.org>]

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 3.14-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-3.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Fri Jul  3 19:59:07 PDT 2015
From: Eric Dumazet <edumazet@google.com>
Date: Tue, 16 Jun 2015 07:59:11 -0700
Subject: packet: read num_members once in packet_rcv_fanout()

From: Eric Dumazet <edumazet@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 <edumazet@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/packet/af_packet.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1345,7 +1345,7 @@ 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 = ACCESS_ONCE(f->num_members);
 	struct packet_sock *po;
 	unsigned int idx;
 


Patches currently in stable-queue which might be from edumazet@google.com are

queue-3.14/packet-avoid-out-of-bounds-read-in-round-robin-fanout.patch
queue-3.14/net-don-t-wait-for-order-3-page-allocation.patch
queue-3.14/tcp-do-not-call-tcp_fastopen_reset_cipher-from-interrupt-context.patch
queue-3.14/packet-read-num_members-once-in-packet_rcv_fanout.patch
queue-3.14/neigh-do-not-modify-unlinked-entries.patch