[PATCH] serial: 8250: use initializer instead of memset to clear local struct

Hi Greg,


2016-12-23 16:20 GMT+09:00 Greg Kroah-Hartman [off-list ref]:

On Fri, Dec 23, 2016 at 12:21:48PM +0900, Masahiro Yamada wrote:

quoted

Leave the way of zero-out to the compiler's decision; the compiler
may know a more optimized way than calling memset().

But no, it doesn't, it will leave "blank" areas in the structure with
bad data in it, which is why we do memset.  See the tree-wide fixups we
made about a year ago for this very issue.  Are you sure none of these
structures get copied to userspace?

I have to admit no security consideration was in my mind.

If we talk about the particular case of struct uart_8250_port,
this structure is allocated in the stack temporarily,
then serial8250_register_8250_port() copies its members to another
structure one by one.  So no "blank" area is exposed to the user-space,
I think.

Having said that, we have no good reason to take a risk for this.

So, please feel free to discard this patch.


-- 
Best Regards
Masahiro Yamada