static void update_audio_tstamp(struct snd_pcm_substream *substream,
				struct timespec *curr_tstamp,
				struct timespec *audio_tstamp)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	u64 audio_frames, audio_nsecs;
	struct timespec driver_tstamp;

	if (runtime->tstamp_mode != SNDRV_PCM_TSTAMP_ENABLE)
		return;

	if (!(substream->ops->get_time_info) ||
		(runtime->audio_tstamp_report.actual_type ==
			SNDRV_PCM_AUDIO_TSTAMP_TYPE_DEFAULT)) {

		/*
		 * provide audio timestamp derived from pointer position
		 * add delay only if requested
		 */

		audio_frames = runtime->hw_ptr_wrap + runtime->status->hw_ptr;

		if (runtime->audio_tstamp_config.report_delay) {
			if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
				audio_frames -=  runtime->delay;
			else
				audio_frames +=  runtime->delay;
		}
		audio_nsecs = div_u64(audio_frames * 1000000000LL,
				runtime->rate);
		*audio_tstamp = ns_to_timespec(audio_nsecs);
	}
	runtime->status->audio_tstamp = *audio_tstamp;
	runtime->status->tstamp = *curr_tstamp;

	/*
	 * re-take a driver timestamp to let apps detect if the reference tstamp
	 * read by low-level hardware was provided with a delay
	 */
	snd_pcm_gettime(substream->runtime, (struct timespec *)&driver_tstamp);
	runtime->driver_tstamp = driver_tstamp;
}

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.