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

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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>
This commit is contained in:
Daniel Borkmann 2013-06-12 16:02:27 +02:00 committed by David S. Miller
parent 631f24a2fe
commit 2dc85bf323
1 changed files with 2 additions and 3 deletions
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5
net/packet/af_packet.c
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@ -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);