[Png-mng-security] libpng-1.0.21rc1, 1.2.13rc1, and 1.4.0beta13

[Dimitri]

Hi,

> They contain fixes for the two just-mentioned vulnerabilities.
> Please review and test, but don't advertize or redistribute them.

About the following change in pngconf.h:
	#  if defined(XP_MACOSX) && !defined(PNG_NO_MMX_CODE)
	     /* work around Intel-Mac compiler bug */
	#    define PNG_NO_MMX_CODE
	#  endif

I wasn't aware of this issue and the only reference I was able to find 
using is:
http://support.realsoftware.com/listarchives/realbasic-plugins/2006-10/msg00037.html
http://support.realsoftware.com/listarchives/realbasic-plugins/2006-10/msg00044.html

The second message seems to imply that disabling MMX is not a solution:
	pnggccrd.c despite it's name, does not get along with Apple's
	GCC4, even when ASM and MMX are disabled (i.e., the "optimized"
	C path crashes too).
So does PNG_NO_MMX_CODE fix the problem or not? If not, maybe this 
change shouldn't go into 1.2.13?

--
Dimitri