Simple Directmedia Layer
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Sam Lantinga 1da252c2d8 Fixed crash in bug 3367 - RGBA_FROM_PIXEL macro can't handle SDL_PIXELFORMAT_ARGB2101010
Simon Hug

The RGBA_FROM_PIXEL macro in src/video/blit.h [1] is not designed to work with more than 8 bits per channel and the ARGB2101010 format makes it read outside of the array bounds causing access violations. This can happen during blitting with the BlitNtoNPixelAlpha and SDL_Blit_Slow functions.

When SDL_InitFormat tries to calculate the loss of the channels [2], the Uint8 will wrap around and it will end up at 254 for the 10-bit channels. Clearly way over the 9 entries of the SDL_expand_byte array. (Not that a signed integer would help.) Then the macro tries to access the lookup table with the channel value which could be up to 1023. If the previous indirection didn't cause an access violation this one will.

I guess it's not worth modifying this macro for a format that only a few will use. It will only make the other blitters slower. I don't have good ideas to solve this issue.

Attached is a test case that does three blits. A copy one that work and the two that use the functions mentioned above.

[1] https://hg.libsdl.org/SDL/file/cd1994d4f3c6/src/video/SDL_blit.h#l303
[2] https://hg.libsdl.org/SDL/file/cd1994d4f3c6/src/video/SDL_pixels.c#l540
2017-08-11 18:56:41 -07:00
acinclude Fixed bug 3481 - Configure fails to detect dynamic library support on powerpc64le 2016-11-06 20:26:48 -08:00
android-project Fixed bug 3464 - Fix for Android hint SDL_HINT_ANDROID_SEPARATE_MOUSE_AND_TOUCH 2017-08-11 13:37:40 -07:00
build-scripts Disable static builds for static analysis. 2017-07-30 14:36:01 -04:00
cmake cmake: whoops, Sam and I both fixed this bug at the same time. :) 2017-08-09 22:34:45 -04:00
debian We don't actually build with the Xt library 2017-01-10 23:23:32 -08:00
docs README-linux.md: added libsndio-dev to the package list. 2017-08-07 00:36:45 -04:00
include Fixed bug 3492 - SDL_RenderCopyEx angle direction not documented 2017-08-11 13:24:18 -07:00
src Fixed crash in bug 3367 - RGBA_FROM_PIXEL macro can't handle SDL_PIXELFORMAT_ARGB2101010 2017-08-11 18:56:41 -07:00
test Fixed bug 3639 - SDL_GetPrefPath returns a path with two consecutive slashes on Unix if org is omitted 2017-08-11 11:32:00 -07:00
VisualC Updated Visual Studio 2008 project 2017-07-10 15:55:13 -07:00
VisualC-WinRT WinRT: removed Windows 8.0 from build-bot + NuGet package creation scripts 2017-02-25 21:23:12 -05:00
visualtest Updated copyright for 2017 2017-01-01 18:33:28 -08:00
Xcode Updated copyright for 2017 2017-01-01 18:33:28 -08:00
Xcode-iOS ios: Fixed math include in demos. 2017-05-25 23:01:59 +02:00
.hgignore audio: Initial bits to enable audio capture support. 2016-08-01 00:18:56 -04:00
Android.mk Make sure the memory barrier functions are always available, and now they are implemented on Android __ARM_ARCH_5TE__ 2017-02-10 11:21:15 -08:00
autogen.sh Don't use pushd/popd in autogen.sh; Ubuntu's /bin/sh doesn't support it. 2016-12-26 22:58:58 -05:00
BUGS.txt BUGS.txt: Changed mailing list link to discourse.libsdl.org. 2017-04-01 00:05:25 -04:00
cmake_uninstall.cmake.in Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
CMakeLists.txt cmake: Pacify warning about Policy CMP0042 not being set. 2017-08-09 22:43:16 -04:00
configure haiku: non-x86 spins use a normal libstdc++ filename. Handle the differences. 2017-08-09 18:41:59 -04:00
configure.in haiku: non-x86 spins use a normal libstdc++ filename. Handle the differences. 2017-08-09 18:41:59 -04:00
COPYING.txt Updated copyright for 2017 2017-01-01 18:33:28 -08:00
CREDITS.txt Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
INSTALL.txt More HTTPS doc tweaks. 2017-02-16 16:59:07 -05:00
Makefile.in Fixed bug 3651 - CMake build does not install CMake package configuration 2017-08-09 19:03:10 -07:00
Makefile.minimal Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
Makefile.pandora pandora: Fixed compiler warning about redefining SDL_REVISION. 2017-06-18 23:00:27 +02:00
Makefile.psp PSP: Added missing object for generic TLS to Makefile. 2016-02-13 17:34:14 +01:00
Makefile.wiz Pandora: Updated SDL version in Makefile. 2016-07-19 21:01:30 +02:00
README-SDL.txt More HTTPS changes in the documentation. 2017-02-16 16:52:03 -05:00
README.txt readme: correct webpage URL to use HTTPS. 2017-02-16 13:30:34 -05:00
sdl2-config.cmake.in Applied Ubuntu patch bug_822210_fix_sdl2-config.cmake_whitespace.patch 2016-10-07 15:08:37 -07:00
sdl2-config.in Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
sdl2.m4 Fixed bug 3429 - Update AM_PATH_SDL2() to also check for SDL2.framework 2016-09-29 16:37:08 -07:00
sdl2.pc.in Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
SDL2.spec.in Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
SDL2Config.cmake Fixed bug 3651 - CMake build does not install CMake package configuration 2017-08-09 19:03:10 -07:00
TODO.txt Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
VisualC.html Fixed two typos in documentation. 2016-01-12 22:23:53 +01:00
WhatsNew.txt Added note for David Carlier's work on OpenBSD 2016-10-12 18:57:12 -07:00

                         Simple DirectMedia Layer

                                  (SDL)

                                Version 2.0

---
https://www.libsdl.org/

Simple DirectMedia Layer is a cross-platform development library designed
to provide low level access to audio, keyboard, mouse, joystick, and graphics
hardware via OpenGL and Direct3D. It is used by video playback software,
emulators, and popular games including Valve's award winning catalog
and many Humble Bundle games.

More extensive documentation is available in the docs directory, starting
with README.md

Enjoy!
	Sam Lantinga				(slouken@libsdl.org)