[PATCH 1/2] drm/bridge: sii902x: re-order conditions to prevent out of bounds read

[Dan Carpenter]

On Fri, Jun 07, 2019 at 09:39:57AM +0200, walter harms wrote:
> 
> 
> Am 07.06.2019 09:27, schrieb Dan Carpenter:
> > This should check that "i" is within bounds before checking reading from
> > the array.
> > 
> > Fixes: ff5781634c41 ("drm/bridge: sii902x: Implement HDMI audio support")
> > Signed-off-by: Dan Carpenter <dan.carpenter at oracle.com>
> > ---
> >  drivers/gpu/drm/bridge/sii902x.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/bridge/sii902x.c b/drivers/gpu/drm/bridge/sii902x.c
> > index d6f98d388ac2..6b03616d6bc3 100644
> > --- a/drivers/gpu/drm/bridge/sii902x.c
> > +++ b/drivers/gpu/drm/bridge/sii902x.c
> > @@ -589,8 +589,8 @@ static int sii902x_audio_hw_params(struct device *dev, void *data,
> >  	if (ret)
> >  		goto out;
> >  
> > -	for (i = 0; sii902x->audio.i2s_fifo_sequence[i] &&
> > -		     i < ARRAY_SIZE(sii902x->audio.i2s_fifo_sequence); i++)
> > +	for (i = 0; i < ARRAY_SIZE(sii902x->audio.i2s_fifo_sequence) &&
> > +		    sii902x->audio.i2s_fifo_sequence[i]; i++)
> >  		regmap_write(sii902x->regmap,
> >  			     SII902X_TPI_I2S_ENABLE_MAPPING_REG,
> >  			     sii902x->audio.i2s_fifo_sequence[i]);
> 
> 
> mmmh, i am a big fan of KISS and in this case i would check sii902x->audio.i2s_fifo_sequence[i]
> outside for(). like:
> 
> 	 for (i = 0; i < ARRAY_SIZE(sii902x->audio.i2s_fifo_sequence); i++) {
> 	        if (!sii902x->audio.i2s_fifo_sequence[i])
>                          break;

That's probably a better way, but either way is acceptable and I left it
how the author wrote it.

regards,
dan carpenter