brk's zero-fill behavior on VAXen

[Daniel R. Levy]

In article <7208 at elsie.UUCP>, ado at elsie.UUCP (Arthur David Olson) writes:
>In section 2 of the UNIX Programmer's Manual, the description of the "brk" and
>"sbrk" calls note only that they change the system's notion of the lowest
>location not used by the program.  If the result of the call is to expand the
>address space of the process, there's no promise about the contents of the
>newly-available address space.  Yet on our VAX (and on yours, too, if you
>have one) the newly-available space is always zero filled.
>
>Can system performance be improved by avoiding zero filling of the new
>memory?

Possibly, but it would also create a security hole where one user could examine
random hunks of memory left behind by other users' processes.  Zeroing is the
quickest way to destroy this data.
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