Re: [PATCH 06/20] staging/lustre: fix comparison between signed and unsigned

Greg Kroah-Hartman
2015-02-02T15:44:03Z

On Mon, Feb 02, 2015 at 04:02:31PM +0300, Dan Carpenter wrote:
> On Sun, Feb 01, 2015 at 09:52:05PM -0500, green@linuxhacker.ru wrote:
> > From: Dmitry Eremin <dmitry.eremin@intel.com>
> >
> > Expression if (size != (ssize_t)size) is always false.
> > Therefore no bounds check errors detected.
>
> The original code actually worked as designed. The integer overflow
> could only happen on 32 bit systems and the test only was true for 32
> bit systems.
>
> > - if (size != (ssize_t)size)
> > + if (size > ~((size_t)0)>>1)
> > return -1;
>
> The problem is that the code was unclear. I think the new code is even
> more complicated to look at.

I agree, I don't even understand what the new code is doing.

What is this code supposed to be protecting from? And -1? That should
never be a return value...

thanks,

greg k-h