[v2] sprof: check pread size and offset for overflow

[DJ Delorie]

Collin Funk <collin.funk1@gmail.com> writes:
> I think that we should check for overflows in this case. I could
> construct an ELF file where the following expression overflows:
>
>     (ehdr->e_shnum * sizeof (ElfW (Shdr)) + ehdr->e_shoff

I would check for this with something like:

	if (ehdr->e_shnum > filesize / sizeof (ElfW (Shdr)))
          error ("too many section numbers")

The above won't overflow, and reports the problem directly.