From: Chetan Loke <loke.chetan@gmail.com>
Date: Thu, 14 Jul 2011 15:36:33 +0000 (-0700)
Subject: af-packet: fix - avoid reading stale data
X-Git-Url: https://openfabrics.org/gitweb/?a=commitdiff_plain;h=cc9f01b246ca8e4fa245991840b8076394f86707;p=~shefty%2Frdma-dev.git

af-packet: fix - avoid reading stale data

Currently we flush tp_status and then flush the remainder of the header+payload.
tp_status should be flushed in the end to avoid stale data being read by user-space.

Incorrectly re-ordered barriers in v1.

Signed-off-by: Chetan Loke <loke.chetan@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index d2294ad1a89..c698cec0a44 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1129,7 +1129,6 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
 	else
 		sll->sll_ifindex = dev->ifindex;
 
-	__packet_set_status(po, h.raw, status);
 	smp_mb();
 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE == 1
 	{
@@ -1138,8 +1137,10 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
 		end = (u8 *)PAGE_ALIGN((unsigned long)h.raw + macoff + snaplen);
 		for (start = h.raw; start < end; start += PAGE_SIZE)
 			flush_dcache_page(pgv_to_page(start));
+		smp_wmb();
 	}
 #endif
+	__packet_set_status(po, h.raw, status);
 
 	sk->sk_data_ready(sk, 0);