Undefined-behavior overflows in GMP?
tg at gmplib.org
Tue Nov 20 10:26:31 CET 2012
Marc Glisse <marc.glisse at inria.fr> writes:
On Tue, 20 Nov 2012, Roberto Bagnara wrote:
> I have just finished reading "Understanding Integer Overflow in C/C++",
> by Will Dietz, Peng Li, John Regehr, and Vikram Adve
> On page 9, it says:
> Finally, we reported nine undefined overflows
> in the GNU Multiple Precision Arithmetic Library, one in
> BIND, and one in OpenSSL. We received no response from
> the developers of these three packages.
> Talking about GMP alone, is this accurate and up to date?
> Would it be possible to see the reports that were sent?
Date: Fri, 20 Aug 2010 21:34:40 -0600
I don't think these things are truly alarming. The C standard defines
lots of thing wrt signed integer types as undefined. We avoid most of
them, but not all. This is not a practical problem. The only related
thing we should really avoid is right-shift of signed types.
When I now look at mpz/cmp.c and cannot correlate any of the reported
problems with the code.
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