[34-longterm 144/209] net: packet: fix information leak to userland

From: Paul Gortmaker
Date: Thu Apr 14 2011 - 14:16:00 EST

From: Vasiliy Kulikov <segooon@xxxxxxxxx>

| This is a commit scheduled for the next v2.6.34 longterm release. |
| If you see a problem with using this for longterm, please comment.|

commit 67286640f638f5ad41a946b9a3dc75327950248f upstream

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@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
net/packet/af_packet.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 243946d..b1bc2d2 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1645,7 +1645,7 @@ static int packet_getname_spkt(struct socket *sock, struct sockaddr *uaddr,
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);
memset(uaddr->sa_data, 0, 14);
@@ -1668,6 +1668,7 @@ 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;
dev = dev_get_by_index_rcu(sock_net(sk), po->ifindex);
if (dev) {

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