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Re: [Tinycc-devel] Proposal for handling alloca(). Anyone see a problem
David A. Wheeler
Re: [Tinycc-devel] Proposal for handling alloca(). Anyone see a problem with it?
Mon, 07 May 2007 22:48:19 -0400 (EDT)
I said earlier:
> So maybe it's not so hard to implement alloca() traditionally... I'll need to
> investigate how it interacts with the buffer-overflow detection stuff
After looking over the original papers about it, and the tcc code, doing the
buffer-overflow stuff for alloca() looks pretty easy!
It appears that alloca() just needs to call __bound_new_region(void *p,
unsigned long size). Since alloca()'ed code may be an array, to make it work
with bounds-checking, alloca should reserve at least one more byte (I'd reserve
4 more bytes, for alignment).
I expected much more nastiness in the details, but I don't see any problems
with it at all now.
Maybe alloca on-the-stack isn't so bad at all! I'm going to give this a go,
and see how it flies. Thanks to all for your help.
--- David A. Wheeler
Re: [Tinycc-devel] Proposal for handling alloca(). Anyone see a problem with it?, Rob Landley, 2007/05/07