Created attachment 2813 [details]
Patch that fixes a possible NULL-pointer indirection in SDL_GL_GetAttribute.

SDL_GL_GetAttribute doesn't check if a video driver has been initialized and will access the SDL_VideoDevice pointer, which is NULL at that point.

I think all of the attributes require an initialized driver, so a simple NULL check should fix it. Patch is attached.

Test case:

#include <SDL.h>

int main(int argc, char*argv[])
{
    int val, res;

    res = SDL_GL_GetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, &val);
    if (res != 0)
        SDL_Log("Error getting attribute before init (%d): %s\n", res, SDL_GetError());
    else
        SDL_Log("Major version set to %d\n", val);

    res = SDL_Init(SDL_INIT_VIDEO);
    if (res != 0)
        SDL_Log("Error initializing SDL (%d): %s\n", res, SDL_GetError());

    res = SDL_GL_GetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, &val);
    if (res != 0)
        SDL_Log("Error getting attribute after init (%d): %s\n", res, SDL_GetError());
    else
        SDL_Log("Major version set to %d\n", val);

    SDL_Quit();
    return 0;
}