From 2dc85bf323515e59e15dfa858d1472bb25cad0fe Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Wed, 12 Jun 2013 16:02:27 +0200 Subject: [PATCH] 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 Signed-off-by: David S. Miller --- net/packet/af_packet.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 8ec1bca7f859..20a1bd0e6549 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -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); -- 2.20.1