Date: Sat, 2 Feb 2008 22:08:05 +0100 SDL-1.2
authorRyan C. Gordon <icculus@icculus.org>
Mon, 04 Feb 2008 17:22:56 +0000
branchSDL-1.2
changeset 4137be12463f31ea
parent 4136 8797fa6e2fb2
child 4138 b1fd24d62e55
Date: Sat, 2 Feb 2008 22:08:05 +0100
From: Marcus von Appen
To: sdl@lists.libsdl.org
Subject: [SDL] [Patch] SDL-1.2 SDL_revcpy() asm patch for the cld flag

Hi,

as reported through the FreeBSD bug tracking system in SDL 1.2.13 (and
in the 1.2 branch, if I see that correctly) the SDL_revcpy() macro sets
the direction flag (std), but does not clear it afterwards (cld), which
is wrong according to the GCC and SYS V specs. This can cause some
weird side effects, which in turn can lead to memory corruption.

You can read the full report with a detailed description and test
program at http://www.freebsd.org/cgi/query-pr.cgi?pr=ports/120052

Attached is the submitted patch, which fixes the issue.

Regards
Marcus
include/SDL_stdinc.h
     1.1 --- a/include/SDL_stdinc.h	Fri Jan 25 05:48:08 2008 +0000
     1.2 +++ b/include/SDL_stdinc.h	Mon Feb 04 17:22:56 2008 +0000
     1.3 @@ -331,6 +331,7 @@
     1.4  	__asm__ __volatile__ (				\
     1.5  		"std\n\t"				\
     1.6  		"rep ; movsl\n\t"			\
     1.7 +		"cld\n\t"				\
     1.8  		: "=&c" (u0), "=&D" (u1), "=&S" (u2)	\
     1.9  		: "0" (n >> 2),				\
    1.10  		  "1" (dstp+(n-4)), "2" (srcp+(n-4))	\