Fixed bug 3852 - SDL_FreeSurface deallocates surface->map even if the surface is not yet freed

Evgeny Kapun

Commit 490bb5b49f11 [1], which was a fix for bug #3790, introduced a new bug: now, calling SDL_FreeSurface(surface) deallocates surface->map even if there are other references to the surface. This is bad, because some functions (such as SDL_ConvertSurface) assume that surface->map is not NULL.

src/video/SDL_surface.c

@@ -1198,10 +1198,8 @@ SDL_FreeSurface(SDL_Surface * surface)
     if (surface->flags & SDL_DONTFREE) {
         return;
     }
-    if (surface->map != NULL) {
-        SDL_FreeBlitMap(surface->map);
-        surface->map = NULL;
-    }
+    SDL_InvalidateMap(surface->map);
+
     if (--surface->refcount > 0) {
         return;
     }