netdev - [PATCH v3 2/3] packet: fill the gap of TPACKET

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Message-ID: <87ob4h6wq1.wl%atzm@stratosphere.co.jp>
Date:	Mon, 16 Dec 2013 17:12:06 +0900
From:	Atzm Watanabe <atzm@...atosphere.co.jp>
To:	netdev@...r.kernel.org
Cc:	"Stephen Hemminger" <stephen@...workplumber.org>,
	"Ben Hutchings" <bhutchings@...arflare.com>,
	"David Miller" <davem@...emloft.net>,
	"Daniel Borkmann" <dborkman@...hat.com>,
	"David Laight" <David.Laight@...LAB.COM>
Subject: [PATCH v3 2/3] packet: fill the gap of TPACKET_ALIGNMENT with zeros

struct tpacket{2,3}_hdr is aligned to a multiple of TPACKET_ALIGNMENT.
Explicitly defining and zeroing the gap of this makes additional changes
easier.

Signed-off-by: Atzm Watanabe <atzm@...atosphere.co.jp>
---
 include/uapi/linux/if_packet.h | 3 ++-
 net/packet/af_packet.c         | 5 ++++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/include/uapi/linux/if_packet.h b/include/uapi/linux/if_packet.h
index 1e24aa7..9185dc9 100644
--- a/include/uapi/linux/if_packet.h
+++ b/include/uapi/linux/if_packet.h
@@ -133,7 +133,7 @@ struct tpacket2_hdr {
 	__u32		tp_sec;
 	__u32		tp_nsec;
 	__u16		tp_vlan_tci;
-	__u16		tp_padding;
+	__u8		tp_padding[6];
 };
 
 struct tpacket_hdr_variant1 {
@@ -154,6 +154,7 @@ struct tpacket3_hdr {
 	union {
 		struct tpacket_hdr_variant1 hv1;
 	};
+	__u8		tp_padding[12];
 };
 
 struct tpacket_bd_ts {
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 1c8b982..5c75a1d 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1929,8 +1929,9 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
 		} else {
 			h.h2->tp_vlan_tci = 0;
 		}
-		h.h2->tp_padding = 0;
 		hdrlen = sizeof(*h.h2);
+		memset(h.h2->tp_padding, 0,
+		       hdrlen - offsetof(struct tpacket2_hdr, tp_padding));
 		break;
 	case TPACKET_V3:
 		/* tp_nxt_offset,vlan are already populated above.
@@ -1944,6 +1945,8 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
 		h.h3->tp_sec  = ts.tv_sec;
 		h.h3->tp_nsec = ts.tv_nsec;
 		hdrlen = sizeof(*h.h3);
+		memset(h.h3->tp_padding, 0,
+		       hdrlen - offsetof(struct tpacket3_hdr, tp_padding));
 		break;
 	default:
 		BUG();
-- 
1.8.1.5

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