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Fixed bug 3544 - Memory freeing bug in SDL_DestroyRenderer/SDL_DestroyTexture 

felix

Here's a snippet of SDL_DestroyRenderer from hg revision 10746:7540ff5d0e0e:

    SDL_Texture *texture = NULL;
    SDL_Texture *nexttexture = NULL;
    /* ... */
    for (texture = renderer->textures; texture; texture = nexttexture) {
        nexttexture = texture->next;
        SDL_DestroyTexture(texture);
    }

SDL_DestroyTexture removes the texture from the linked list pointed to by the renderer and ends up calling SDL_DestroyTextureInternal, which contains this:

    if (texture->native) {
        SDL_DestroyTexture(texture->native);
    }

If it happens that texture->native is an alias of nexttexture two stack frames up, SDL_DestroyRenderer will end up trying to destroy an already freed texture. I've had this very situation happen in dosemu2.

Bug introduced in revision 10650:a8253d439914, which has a somewhat ironic description of "Fixed all known static analysis bugs"...
Sam Lantinga 2017-01-06 00:32:06 -08:00
parent 345c5989f1
commit 356c2eadf4
1 changed files with 2 additions and 4 deletions
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6
src/render/SDL_render.c
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@ -1951,11 +1951,9 @@ SDL_DestroyRenderer(SDL_Renderer * renderer)
/* Free existing textures for this renderer */ /* Free existing textures for this renderer */
SDL_SetRenderTarget(renderer, NULL); SDL_SetRenderTarget(renderer, NULL);
for (texture = renderer->textures; texture; texture = nexttexture) { while (renderer->textures) {
nexttexture = texture->next; SDL_DestroyTexture(renderer->textures);
SDL_DestroyTexture(texture);
} }
renderer->textures = NULL;
if (renderer->window) { if (renderer->window) {
SDL_SetWindowData(renderer->window, SDL_WINDOWRENDERDATA, NULL); SDL_SetWindowData(renderer->window, SDL_WINDOWRENDERDATA, NULL);