net: packet: fix information leak to userland

[ Upstream commit 67286640f638f5ad41a946b9a3dc75327950248f ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index c615b0f73b92cfd3b6a5a3a1e03a1d4f3b10b536..9ba70146a4fe0e604d387a7556c6ff7fee7c57b9 100644 (file)
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1721,7 +1721,7 @@ 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();
@@ -1744,6 +1744,7 @@ 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) {