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Subject[31/35] af_packet: prevent information leak
2.6.32-longterm review patch.  If anyone has any objections, please let us know.

------------------

From: Eric Dumazet <eric.dumazet@gmail.com>

[ Upstream commit 13fcb7bd322164c67926ffe272846d4860196dc6 ]

In 2.6.27, commit 393e52e33c6c2 (packet: deliver VLAN TCI to userspace)
added a small information leak.

Add padding field and make sure its zeroed before copy to user.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
include/linux/if_packet.h | 2 ++
net/packet/af_packet.c | 2 ++
2 files changed, 4 insertions(+)
--- a/include/linux/if_packet.h
+++ b/include/linux/if_packet.h
@@ -63,6 +63,7 @@ struct tpacket_auxdata
__u16 tp_mac;
__u16 tp_net;
__u16 tp_vlan_tci;
+ __u16 tp_padding;
};

/* Rx ring - header status */
@@ -103,6 +104,7 @@ struct tpacket2_hdr
__u32 tp_sec;
__u32 tp_nsec;
__u16 tp_vlan_tci;
+ __u16 tp_padding;
};

#define TPACKET2_HDRLEN (TPACKET_ALIGN(sizeof(struct tpacket2_hdr)) + sizeof(struct sockaddr_ll))
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -767,6 +767,7 @@ static int tpacket_rcv(struct sk_buff *s
h.h2->tp_sec = ts.tv_sec;
h.h2->tp_nsec = ts.tv_nsec;
h.h2->tp_vlan_tci = skb->vlan_tci;
+ h.h2->tp_padding = 0;
hdrlen = sizeof(*h.h2);
break;
default:
@@ -1499,6 +1500,7 @@ static int packet_recvmsg(struct kiocb *
aux.tp_net = skb_network_offset(skb);
aux.tp_vlan_tci = skb->vlan_tci;

+ aux.tp_padding = 0;
put_cmsg(msg, SOL_PACKET, PACKET_AUXDATA, sizeof(aux), &aux);
}




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