Messages in this thread | | | From | Paul Mackerras <> | Date | Thu, 3 Jan 2002 14:12:19 +1100 (EST) | Subject | Re: [PATCH] C undefined behavior fix |
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Joe Buck writes:
> There is already such a project under development: see > > http://gcc.gnu.org/projects/bp/main.html > > This is a modification to gcc that implements pointers as triples. > While there is a performance penalty for doing this, it can completely > eliminate the problem of exploitable buffer overflows. However, programs > that violate the rules of ISO C by generating out-of-range pointers will > fail.
What will it do if I cast a pointer to unsigned long? Or if I cast an unsigned long to a pointer? The kernel does both of these things, and in a lot of places.
Part of my beef with what gcc-3 is doing is that I take a pointer, cast it to unsigned long, do something to it, cast it back to a pointer, and gcc _still_ thinks it's knows what I am doing. It doesn't.
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