Fix ali5451 dereferenced before NULL check

Fix ali5451 dereferenced before NULL check

[Eugene Teo]

pvoice is missing a NULL check. channel needs a bound check too.

Coverity bug #862

Signed-off-by: Eugene Teo <eugene.teo@eugeneteo.net>

--- linux-2.6/sound/pci/ali5451/ali5451.c~	2006-03-15 10:05:45.000000000 +0800
+++ linux-2.6/sound/pci/ali5451/ali5451.c	2006-03-16 09:27:53.000000000 +0800
@@ -990,7 +990,13 @@
 	if (!(old & mask))
 		return;
 
+	if (channel < 0 || channel >= ALI_CHANNELS)
+		return;
+	
 	pvoice = &codec->synth.voices[channel];
+	if (pvoice == NULL)
+		return;
+
 	runtime = pvoice->substream->runtime;
 
 	udelay(100);

-- 
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); }

Re: Fix ali5451 dereferenced before NULL check

[Takashi Iwai]

At Thu, 16 Mar 2006 09:36:02 +0800,
Eugene Teo wrote:
> 
> pvoice is missing a NULL check. channel needs a bound check too.

Both checks are not necessary.  There is a single caller to this
function, and the channel argument is a loop value of

	for (channel = 0; channel < ALI_CHANNELS; channel++)
		snd_ali_update_ptr(codec, channel);

pvoice is the address pointing a part of a structure, so it cannot be
NULL anyway.  If a check were needed, it should be if (codec != NULL).


Takashi

> 
> Coverity bug #862
> 
> Signed-off-by: Eugene Teo <eugene.teo@eugeneteo.net>
> 
> --- linux-2.6/sound/pci/ali5451/ali5451.c~	2006-03-15 10:05:45.000000000 +0800
> +++ linux-2.6/sound/pci/ali5451/ali5451.c	2006-03-16 09:27:53.000000000 +0800
> @@ -990,7 +990,13 @@
>  	if (!(old & mask))
>  		return;
>  
> +	if (channel < 0 || channel >= ALI_CHANNELS)
> +		return;
> +	
>  	pvoice = &codec->synth.voices[channel];
> +	if (pvoice == NULL)
> +		return;
> +
>  	runtime = pvoice->substream->runtime;
>  
>  	udelay(100);
> 
> -- 
> 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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Re: Fix ali5451 dereferenced before NULL check

[Eugene Teo]

Hi Takashi-san,

<quote sender="Takashi Iwai">
> At Thu, 16 Mar 2006 09:36:02 +0800,
> Eugene Teo wrote:
> > 
> > pvoice is missing a NULL check. channel needs a bound check too.
> 
> Both checks are not necessary.  There is a single caller to this
> function, and the channel argument is a loop value of

All right.

> 	for (channel = 0; channel < ALI_CHANNELS; channel++)
> 		snd_ali_update_ptr(codec, channel);
> 
> pvoice is the address pointing a part of a structure, so it cannot be
> NULL anyway.  If a check were needed, it should be if (codec != NULL).

A check for codec is unnecessary. snd_ali_card_interrupt() is the only
caller for snd_ali_interrupt() and it checks codec for NULL before it
calls the function to perform the above for loop.

Thanks.

Eugene
-- 
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); }