Re: [PATCH] fbdev: potential information leak in do_fb_ioctl()

From: Eric W. Biederman
Date: Thu Oct 31 2019 - 18:12:26 EST


Joe Perches <joe@xxxxxxxxxxx> writes:

> On Wed, 2019-10-30 at 21:12 +0100, Andrea Righi wrote:
>> Then memset() + memcpy() is probably the best option,
>> since copying all those fields one by one looks quite ugly to me...
>
> A memset of an automatic before a memcpy to the same
> automatic is unnecessary.

You still need to guarantee that all of the holes in the
structure you are copying are initialized before you copy it.

Otherwise you are just changing which unitialized memory that
is being copied to userspace.

Which is my concern with your very simple suggestion.

Eric