net: packet: fix information leak to userland

packet_getname_spkt() doesn't initialize all members of sa_data field of
sockaddr struct if strlen(dev->name) < 13.  This structure is then copied
to userland.  It leads to leaking of contents of kernel stack memory.
We have to fully fill sa_data with strncpy() instead of strlcpy().

The same with packet_getname(): it doesn't initialize sll_pkttype field of
sockaddr_ll.  Set it to zero.

Signed-off-by: Vasiliy Kulikov <segooon@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 3616f27b9d46c08e0f750b47865cc17c3130c5f2..0856a13cb53d8001ff33f48cfd7e048721e476d2 100644 (file)
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1719,7 +1719,7 @@ static int packet_getname_spkt(struct socket *sock, struct sockaddr *uaddr,
        rcu_read_lock();
        dev = dev_get_by_index_rcu(sock_net(sk), pkt_sk(sk)->ifindex);
        if (dev)
-               strlcpy(uaddr->sa_data, dev->name, 15);
+               strncpy(uaddr->sa_data, dev->name, 14);
        else
                memset(uaddr->sa_data, 0, 14);
        rcu_read_unlock();
@@ -1742,6 +1742,7 @@ static int packet_getname(struct socket *sock, struct sockaddr *uaddr,
        sll->sll_family = AF_PACKET;
        sll->sll_ifindex = po->ifindex;
        sll->sll_protocol = po->num;
+       sll->sll_pkttype = 0;
        rcu_read_lock();
        dev = dev_get_by_index_rcu(sock_net(sk), po->ifindex);
        if (dev) {