dcbnl: fix various netlink info leaks

commit 29cd8ae0 upstream.

The dcb netlink interface leaks stack memory in various places:
* perm_addr[] buffer is only filled at max with 12 of the 32 bytes but
  copied completely,
* no in-kernel driver fills all fields of an IEEE 802.1Qaz subcommand,
  so we're leaking up to 58 bytes for ieee_ets structs, up to 136 bytes
  for ieee_pfc structs, etc.,
* the same is true for CEE -- no in-kernel driver fills the whole
  struct,

Prevent all of the above stack info leaks by properly initializing the
buffers/structures involved.
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 2.6.32: no support for IEEE or CEE commands, so only
 deal with perm_addr]
Signed-off-by: Willy Tarreau <w@1wt.eu>

net/dcb/dcbnl.c

@@ -307,6 +307,7 @@ static int dcbnl_getperm_hwaddr(struct net_device *netdev, struct nlattr **tb,
 	dcb->dcb_family = AF_UNSPEC;
 	dcb->cmd = DCB_CMD_GPERM_HWADDR;
 
+	memset(perm_addr, 0, sizeof(perm_addr));
 	netdev->dcbnl_ops->getpermhwaddr(netdev, perm_addr);
 
 	ret = nla_put(dcbnl_skb, DCB_ATTR_PERM_HWADDR, sizeof(perm_addr),