net: ethtool: clear heap allocations for ethtool function

net: ethtool: clear heap allocations for ethtool function

BugLink: https://bugs.launchpad.net/bugs/1936863
[ Upstream commit 80ec82e3d2c1fab42eeb730aaa7985494a963d3f ]

Several ethtool functions leave heap uncleared (potentially) by
drivers. This will leave the unused portion of heap unchanged and
might copy the full contents back to userspace.

Signed-off-by: Austin Kim <austindh.kim@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>