linux-kernel - Re: [PATCH] sound: hdmi: avoid dereferencing uninitialized 'jack' pointer

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Message-ID: <12468747.ft2nGomr6c@wuerfel>
Date:	Tue, 16 Feb 2016 18:09:11 +0100
From:	Arnd Bergmann <arnd@...db.de>
To:	linux-arm-kernel@...ts.infradead.org
Cc:	alsa-devel@...a-project.org, Takashi Iwai <tiwai@...e.de>,
	linux-kernel@...r.kernel.org, Jaroslav Kysela <perex@...ex.cz>,
	Mark Brown <broonie@...nel.org>, Han Lu <han.lu@...el.com>,
	Libin Yang <libin.yang@...ux.intel.com>,
	Thierry Reding <treding@...dia.com>,
	David Henningsson <david.henningsson@...onical.com>
Subject: Re: [PATCH] sound: hdmi: avoid dereferencing uninitialized 'jack' pointer

On Tuesday 16 February 2016 17:59:04 Arnd Bergmann wrote:
> --- a/sound/pci/hda/hda_jack.c
> +++ b/sound/pci/hda/hda_jack.c
> @@ -403,8 +403,10 @@ int snd_hda_jack_add_kctl(struct hda_codec *codec, hda_nid_t nid,
>  
>         jack->phantom_jack = !!phantom_jack;
>         jack->type = type;
> -       jack->jack->private_data = jack;
> -       jack->jack->private_free = hda_free_jack_priv;
> +       if (IS_ENABLED(CONFIG_SND_JACK)) {
> +               jack->jack->private_data = jack;
> +               jack->jack->private_free = hda_free_jack_priv;
> +       }
>         state = snd_hda_jack_detect(codec, nid);
>         snd_jack_report(jack->jack, state ? jack->type : 0);
>  

Or another idea: if we pass private_{data,free} into snd_jack_new()
as arguments, the snd_jack structure can become private to
sound/core/jack.c, so we can be sure to never hit this bug
again.

	Arnd