af_packet: prevent information leak
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>
diff --git a/include/linux/if_packet.h b/include/linux/if_packet.h
index 6d66ce1..7b31863 100644
--- a/include/linux/if_packet.h
+++ b/include/linux/if_packet.h
@@ -62,6 +62,7 @@
__u16 tp_mac;
__u16 tp_net;
__u16 tp_vlan_tci;
+ __u16 tp_padding;
};
/* Rx ring - header status */
@@ -101,6 +102,7 @@
__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))
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index ba248d9..c0c3cda 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -804,6 +804,7 @@
} else {
h.h2->tp_vlan_tci = 0;
}
+ h.h2->tp_padding = 0;
hdrlen = sizeof(*h.h2);
break;
default:
@@ -1736,6 +1737,7 @@
} else {
aux.tp_vlan_tci = 0;
}
+ aux.tp_padding = 0;
put_cmsg(msg, SOL_PACKET, PACKET_AUXDATA, sizeof(aux), &aux);
}