Full Disclosure mailing list archives
Re: Firefox 2.0.0.7 has a very serious calculation bug
From: Rodrigo Barbosa <rodrigob () darkover org>
Date: Fri, 28 Sep 2007 16:44:02 -0300
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Fri, Sep 28, 2007 at 09:09:02PM +0200, Michal Zalewski wrote:
On Sat, 29 Sep 2007, Jimby Sharp wrote:I don't get the same from C-style double arithmetics. Could you provide a sample code that you believe should show the same behavior?If you don't, it's presumably because the subtraction is optimized out by the compiler, or because you printf() with an insufficient precision in format spec. The following should do the trick: volatile double a = 5.2; volatile double b = 0.1; main() { printf("%.16lf\n",a-b); }
Isn't this the same issue pointed out by Brian Kim (double to float conversion) ? Look the results I get for the following code: volatile double a = 5.2; volatile double b = 0.1; main() { printf("%.16lf\n",a); printf("%.16lf\n",b); printf("%.16lf\n",(volatile double) 5.1); printf("%.16lf\n",(volatile double)((float) 5.1)); printf("%.16lf\n",a-b); } Results: 5.2000000000000002 0.1000000000000000 5.0999999999999996 5.0999999046325684 <------------ 5.1000000000000005 - -- Rodrigo Barbosa "Quid quid Latine dictum sit, altum viditur" "Be excellent to each other ..." - Bill & Ted (Wyld Stallyns) -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (GNU/Linux) iD8DBQFG/VmCpdyWzQ5b5ckRArw8AJ9snBYsgIK7pvwHbILw43gTtuz6rwCgqxGO snsqqiu9zDaqhITIe/Ycf7o= =MJfE -----END PGP SIGNATURE----- _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.grok.org.uk/full-disclosure-charter.html Hosted and sponsored by Secunia - http://secunia.com/
Current thread:
- Re: Firefox 2.0.0.7 has a very serious calculation bug, (continued)
- Re: Firefox 2.0.0.7 has a very serious calculation bug James Matthews (Sep 29)
- Re: Firefox 2.0.0.7 has a very serious calculation bug Jimby Sharp (Sep 28)
- Re: Firefox 2.0.0.7 has a very serious calculation bug Mukul Dharwadkar (Sep 28)
- Re: Firefox 2.0.0.7 has a very serious calculation bug Larry Seltzer (Sep 28)
- Re: Firefox 2.0.0.7 has a very serious calculation bug Steven Adair (Sep 28)
- Re: Firefox 2.0.0.7 has a very seriouscalculation bug gjgowey (Sep 28)
- Re: Firefox 2.0.0.7 has a very serious calculation bug Steven Adair (Sep 28)
- Re: Firefox 2.0.0.7 has a very serious calculation bug Larry Seltzer (Sep 28)
- Re: Firefox 2.0.0.7 has a very serious calculation bug Michal Zalewski (Sep 28)
- Re: Firefox 2.0.0.7 has a very serious calculation bug Jimby Sharp (Sep 28)
- Re: Firefox 2.0.0.7 has a very serious calculation bug Michal Zalewski (Sep 28)
- Re: Firefox 2.0.0.7 has a very serious calculation bug Rodrigo Barbosa (Sep 28)
- Re: Firefox 2.0.0.7 has a very serious calculation bug Michal Zalewski (Sep 28)
- Re: Firefox 2.0.0.7 has a very serious calculation bug Jimby Sharp (Sep 28)
- Re: Firefox 2.0.0.7 has a very serious calculation bug Rodrigo Barbosa (Sep 28)
- Re: Firefox 2.0.0.7 has a very serious calculation bug Jimby Sharp (Sep 28)
- Re: Firefox 2.0.0.7 has a very serious calculation bug Brian Kim (Sep 28)
- Re: Firefox 2.0.0.7 has a very serious calculation bug Susam Pal (Sep 28)