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SW Renderer: fix invalid read if VSYNC hint is initially set with an empty value (eg "") 

because:
- GeHint return a value pointer.
- SetHint free internally the pointer
- The -now invalid- pointer is re-read

==9363== Invalid read of size 1
==9363==    at 0x4946860: SW_CreateRenderer (SDL_render_sw.c:1044)
==9363==    by 0x48F0EC3: SDL_CreateRenderer_REAL (SDL_render.c:938)
==9363==    by 0x48C5921: SDL_CreateRenderer (SDL_dynapi_procs.h:332)
==9363==    by 0x401584: main (main.c:421)
==9363==  Address 0x9c24040 is 0 bytes inside a block of size 1 free'd
==9363==    at 0x484621F: free (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
==9363==    by 0x494E403: SDL_free_REAL (SDL_malloc.c:5432)
==9363==    by 0x48A6153: SDL_SetHintWithPriority_REAL (SDL_hints.c:76)
==9363==    by 0x48A6254: SDL_SetHint_REAL (SDL_hints.c:101)
main
Sylvain 2021-12-08 09:41:33 +01:00
parent 9409642e08
commit 1940d289bf
No known key found for this signature in database
GPG Key ID: 5F87E02E5BC0939E
1 changed files with 8 additions and 1 deletions
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9
src/render/software/SDL_render_sw.c
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@ -1030,17 +1030,24 @@ SW_CreateRenderer(SDL_Window * window, Uint32 flags)
{
const char *hint;
SDL_Surface *surface;
SDL_bool no_hint_set;
/* Set the vsync hint based on our flags, if it's not already set */
hint = SDL_GetHint(SDL_HINT_RENDER_VSYNC);
if (!hint || !*hint) {
no_hint_set = SDL_TRUE;
} else {
no_hint_set = SDL_FALSE;
}
if (no_hint_set) {
SDL_SetHint(SDL_HINT_RENDER_VSYNC, (flags & SDL_RENDERER_PRESENTVSYNC) ? "1" : "0");
}
surface = SDL_GetWindowSurface(window);
/* Reset the vsync hint if we set it above */
if (!hint || !*hint) {
if (no_hint_set) {
SDL_SetHint(SDL_HINT_RENDER_VSYNC, "");
}