Out-of-bounds pointers

[Doug Gwyn]

In article <252 at bbxsda.UUCP> scott at bbxsda.UUCP (Scott Amspoker) writes:
>While I fully agree that a pointer to "expired" stack data is to
>be considered "invalid" I am not aware of any implementation that
>actually removes stack memory from the memory map upon exit from
>a procedure.  That would probably slow things down considerably.
>Dereferencing such a pointer would be meaningless but would probably
>not cause a trap (although such a program is certainly headed for a
>trap :-)

Again, the question is NOT about dereferencing the pointer value,
but rather about accessing the now-invalid pointer value at all.

On the same general class of architectures for which it would be a
problem for free()d pointers, it could easily be a problem for
expired activation records (what you would probably call a "stack
frame", but in a true segmented architecture an activation record
is a separate system-controlled object in its own right, normally
reclaimed by the system immediately upon expiration of its
dynamic scope).  I don't know of any C compilers for the B[56]x00
family of computers, but of there are any I would expect them to
exhibit this behavior.