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af_packet: prevent information leak 

In 2.6.27, commit 393e52e33c (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>
This commit is contained in:
Eric Dumazet 2011-06-06 22:42:06 -07:00 committed by David S. Miller
parent 79b3891587
commit 13fcb7bd32
2 changed files with 4 additions and 0 deletions
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2
include/linux/if_packet.h
View File

@ -62,6 +62,7 @@ struct tpacket_auxdata {
__u16 tp_mac;
__u16 tp_net;
__u16 tp_vlan_tci;
__u16 tp_padding;
};
/* Rx ring - header status */
@ -101,6 +102,7 @@ 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))

2
net/packet/af_packet.c
View File

@ -804,6 +804,7 @@ 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);
break;
default:
@ -1736,6 +1737,7 @@ static int packet_recvmsg(struct kiocb *iocb, struct socket *sock,
} else {
aux.tp_vlan_tci = 0;
}
aux.tp_padding = 0;
put_cmsg(msg, SOL_PACKET, PACKET_AUXDATA, sizeof(aux), &aux);
}