Commit 2dc85bf3 authored Jun 12, 2013 by Daniel Borkmann Committed by David S. Miller Jun 13, 2013

packet: packet_getname_spkt: make sure string is always 0-terminated



uaddr->sa_data is exactly of size 14, which is hard-coded here and
passed as a size argument to strncpy(). A device name can be of size
IFNAMSIZ (== 16), meaning we might leave the destination string
unterminated. Thus, use strlcpy() and also sizeof() while we're
at it. We need to memset the data area beforehand, since strlcpy
does not padd the remaining buffer with zeroes for user space, so
that we do not possibly leak anything.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 631f24a2

net/packet/af_packet.c

+2 −3

Original line number	Diff line number	Diff line
		@@ -2851,12 +2851,11 @@ static int packet_getname_spkt(struct socket sock, struct sockaddr uaddr,
		return -EOPNOTSUPP;

		uaddr->sa_family = AF_PACKET;
		memset(uaddr->sa_data, 0, sizeof(uaddr->sa_data));
		rcu_read_lock();
		dev = dev_get_by_index_rcu(sock_net(sk), pkt_sk(sk)->ifindex);
		if (dev)
		strncpy(uaddr->sa_data, dev->name, 14);
		else
		memset(uaddr->sa_data, 0, 14);
		strlcpy(uaddr->sa_data, dev->name, sizeof(uaddr->sa_data));
		rcu_read_unlock();
		uaddr_len = sizeof(uaddr);

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