Fixed bug 2467 - bad memcpy in SDL_OpenAudio/open_audio_device/prepare_audiospec chain

Rainer Deyke

If 'SDL_OpenAudio' is called with 'obtained == NULL', 'prepare_audiospec' performs a bad 'memcpy' with the destination and source pointing to the same block of memory.  The problem appears to be on in 'SDL_OpenAudio', which calls open_audio_device with 'obtained = desired' when 'obtained == NULL'.  'open_audio_device' cannot deal with 'desired' and 'obtained' pointing to the same block of memory but can deal with 'obtained == NULL'

src/audio/SDL_audio.c

@@ -1094,7 +1094,7 @@ SDL_OpenAudio(SDL_AudioSpec * desired, SDL_AudioSpec * obtained)
         id = open_audio_device(NULL, 0, desired, obtained,
                                SDL_AUDIO_ALLOW_ANY_CHANGE, 1);
     } else {
-        id = open_audio_device(NULL, 0, desired, desired, 0, 1);
+        id = open_audio_device(NULL, 0, desired, NULL, 0, 1);
     }
 
     SDL_assert((id == 0) || (id == 1));