Re: drm/i2c: tda998x: use irq for connection status and EDID read - Jean-Francois Moine

From: Jean-Francois Moine <moinejf@free.fr>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: dri-devel@lists.freedesktop.org
Subject: Re: drm/i2c: tda998x: use irq for connection status and EDID read
Date: Mon, 7 Jul 2014 17:54:44 +0200	[thread overview]
Message-ID: <20140707175444.001602a6@armhf> (raw)
In-Reply-To: <20140707142203.GA13469@mwanda>

On Mon, 7 Jul 2014 17:22:03 +0300
Dan Carpenter <dan.carpenter@oracle.com> wrote:

> The patch 12473b7d8e60: "drm/i2c: tda998x: use irq for connection
> status and EDID read" from Jan 25, 2014, leads to the following
> static checker warning:
> 
> 	drivers/gpu/drm/i2c/tda998x_drv.c:1199 tda998x_encoder_destroy()
> 	warn: variable dereferenced before check 'priv->cec' (see line 1194)
> 
> drivers/gpu/drm/i2c/tda998x_drv.c
>   1188  static void
>   1189  tda998x_encoder_destroy(struct drm_encoder *encoder)
>   1190  {
>   1191          struct tda998x_priv *priv = to_tda998x_priv(encoder);
>   1192  
>   1193          /* disable all IRQs and free the IRQ handler */
>   1194          cec_write(priv, REG_CEC_RXSHPDINTENA, 0);
>                 ^^^^^^^^^^^^^^
> We dereference priv->cec inside the call to cec_write().
> 
>   1195          reg_clear(priv, REG_INT_FLAGS_2, INT_FLAGS_2_EDID_BLK_RD);
>   1196          if (priv->hdmi->irq)
>   1197                  free_irq(priv->hdmi->irq, priv);
>   1198  
>   1199          if (priv->cec)
>                     ^^^^^^^^^
> But later in the function we assume that ->cec can be NULL.
> 
>   1200                  i2c_unregister_device(priv->cec);
>   1201          drm_i2c_encoder_destroy(encoder);
>   1202          kfree(priv);
>   1203  }

Yes, priv->cec is never NULL.

Thanks.

-- 
Ken ar c'hentañ	|	      ** Breizh ha Linux atav! **
Jef		|		http://moinejf.free.fr/
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