Function snd_pcm_create() will return a negative number when it fails to create a new PCM instance, thus its return value shall be checked before further manipulations of the created PCM. But in function poseidon_audio_init(), at drivers/media/video/tlg2300/pd-alsa.c:296, there is no checking of the return value of snd_pcm_create() at line 307, which may trigger an invalid memmory access error when dereferencing variable pcm in function snd_pcm_set_ops() called at line 308.
The related codes in function poseidon_audio_init() are as following.
 307        ret = snd_pcm_new(card, "poseidon audio", 0, 0, 1, &pcm);
 308        snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &pcm_capture_ops);
 309        pcm->info_flags   = 0;

Generally, the return value of snd_pcm_create() shall be checked to make sure that the PCM instance is created successfully. Like the following codes from the same device driver.
em28xx_audio_init @@ drivers/media/video/em28xx/em28xx-audio.c:473
 473        err = snd_pcm_new(card, "Em28xx Audio", 0, 0, 1, &pcm);
 474        if (err < 0) {
 475                snd_card_free(card);
 476                return err;
 477        }
 478
 479        snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &snd_em28xx_pcm_capture);
 480        pcm->info_flags = 0;

Thank you

RUC_Soft_Sec