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Commit 13fcb7bd authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

af_packet: prevent information leak 



In 2.6.27, commit 393e52e3 (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: default avatarEric Dumazet <eric.dumazet@gmail.com>
CC: Patrick McHardy <kaber@trash.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 79b38915

include/linux/if_packet.h

+2 −0
Original line number Diff line number Diff line
@@ -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))

net/packet/af_packet.c

+2 −0
Original line number Diff line number Diff line
@@ -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);

	}