gcc puts executable code on the stack frame

[Gary Polhill]

A colleague of mine has installed Swarm on a Sun workstation, and
compiled heatbugs, but found he got segmentation faults when he ran it.
He asked his systems administrator about this and was told that the
Suns in his department have disabled execution of code on the stack,
because this is a security hazard. gcc apparently does put executable
code on the stack through the use of "trampolenes". 

I have very little idea what any of this means, but I think answers to
the following questions would help:

Does anyone know if compiling using egcs instead of gcc would avoid
this problem?

Is the problem due to Swarm in any way?

What is the security risk associated with putting executable code on the
stack? (I.e. what sort of attacks might we be exposing ourselves to by
running programs compiled with gcc?)

Is this an obj-C related problem, or does it apply to gcc in general?

Other than things people jump up and down on for fun, what the hell
are trampolenes?

I'm aware that this question is probably better asked of a different
group altogether. Apologies for this, but the problem arose through the
use of Swarm rather than other programs compiled with gcc. Indeed, I have
successfully compiled and run Swarm 1.0.3 and various applications
associated with it on the same machine. (Though this was before it was
upgraded from Solaris 2.6 to 7.)

Thanks in advance for any responses.

Gary

-- 

Macaulay Land Use Research Institute, Craigiebuckler, Aberdeen. AB15 8QH
Tel: +44 (0) 1224 318611               Email: address@hidden

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