Re: Fix gus_pcm dereference before NULL

[Takashi Iwai]

At Thu, 16 Mar 2006 10:00:07 +0800,
Eugene Teo wrote:
> 
> substream is dereferenced before checking for NULL.

The NULL check of substream is simply superfluous.
It is guaranteed to receive non-NULL substream and
substream->runtime.


Takashi

> 
> Coverity bug #861
> 
> Signed-off-by: Eugene Teo <eugene.teo@xxxxxxxxxxxxx>
> 
> --- linux-2.6/sound/isa/gus/gus_pcm.c~	2006-03-15 10:05:45.000000000 +0800
> +++ linux-2.6/sound/isa/gus/gus_pcm.c	2006-03-16 09:51:43.000000000 +0800
> @@ -103,8 +103,8 @@
>  
>  static void snd_gf1_pcm_trigger_up(struct snd_pcm_substream *substream)
>  {
> -	struct snd_pcm_runtime *runtime = substream->runtime;
> -	struct gus_pcm_private *pcmp = runtime->private_data;
> +	struct snd_pcm_runtime *runtime;
> +	struct gus_pcm_private *pcmp;
>  	struct snd_gus_card * gus = pcmp->gus;
>  	unsigned long flags;
>  	unsigned char voice_ctrl, ramp_ctrl;
> @@ -114,8 +114,10 @@
>  	unsigned char pan;
>  	unsigned int voice;
>  
> -	if (substream == NULL)
> +	if (substream == NULL || substream->runtime == NULL)
>  		return;
> +	runtime = substream->runtime;
> +	pcmp = runtime->private_data;
>  	spin_lock_irqsave(&pcmp->lock, flags);
>  	if (pcmp->flags & SNDRV_GF1_PCM_PFLG_ACTIVE) {
>  		spin_unlock_irqrestore(&pcmp->lock, flags);
> 
> -- 
> 1024D/A6D12F80 print D51D 2633 8DAC 04DB 7265  9BB8 5883 6DAA A6D1 2F80
> main(i) { putchar(182623909 >> (i-1) * 5&31|!!(i<7)<<6) && main(++i); }
> 
> -
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