Re: [PATCH 1/3] libdw: Make srclines use a stable sort

[Mark Wielaard <mjw at redhat dot com>]

On Thu, Dec 11, 2014 at 05:34:06PM -0800, Josh Stone wrote:
> BTW, I want to point out this change in compare_lines:
> 
> > -  return (*p1)->addr - (*p2)->addr;
> [...]
> > +  if (line1->addr != line2->addr)
> > +    return (line1->addr < line2->addr) ? -1 : 1;
> 
> Since addr is 64-bit unsigned, and comparison functions return int, it
> is possible for the difference to be so large that it wraps around.  You
> only need INT_MAX or more -- which probably doesn't happen often in ELF
> files, but it's plausible.
> 
> It might be worth auditing other qsort/tsearch comparison functions for
> similar wrapping possibilities.

I think you are right. I looked over all compare functions and two didn't
do as you suggest. The attached patch fixes those. Do that look correct?

Thanks,

Mark

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