USB: serial/mos*: prevent reading uninitialized stack memory

USB: serial/mos*: prevent reading uninitialized stack memory

commit a0846f1868b11cd827bdfeaf4527d8b1b1c0b098 upstream.

The TIOCGICOUNT device ioctl in both mos7720.c and mos7840.c allows
unprivileged users to read uninitialized stack memory, because the
"reserved" member of the serial_icounter_struct struct declared on the
stack is not altered or zeroed before being copied back to the user.
This patch takes care of it.

Signed-off-by: Dan Rosenberg <dan.j.rosenberg@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>