linux-kernel - Re: [alsa-devel] [PATCH] sound/oss/pss: Fix test of unsigned in pss_reset_dsp() and pss_download_boot()

Open Source and information security mailing list archives

Date:	Wed, 16 Dec 2009 17:23:03 -0700
From:	Troy Kisky <troy.kisky@...ndarydevices.com>
To:	Roel Kluin <roel.kluin@...il.com>
Cc:	Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.de>,
	alsa-devel@...a-project.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [alsa-devel] [PATCH] sound/oss/pss: Fix test of unsigned in pss_reset_dsp()
 and pss_download_boot()

Roel Kluin wrote:
> limit and jiffies are unsigned so the test does not work.
> 
> Signed-off-by: Roel Kluin <roel.kluin@...il.com>
> ---
> Found using coccinelle: http://coccinelle.lip6.fr/
> 
> diff --git a/sound/oss/pss.c b/sound/oss/pss.c
> index 83f5ee2..9325f4d 100644
> --- a/sound/oss/pss.c
> +++ b/sound/oss/pss.c
> @@ -269,7 +269,7 @@ static int pss_reset_dsp(pss_confdata * devc)
>  	unsigned long   i, limit = jiffies + HZ/10;
>  
>  	outw(0x2000, REG(PSS_CONTROL));
> -	for (i = 0; i < 32768 && (limit-jiffies >= 0); i++)

I think
	for (i = 0; i < 32768 && ( (int)(limit-jiffies) >= 0); i++)

works better when jiffies wrap

> +	for (i = 0; i < 32768 && (limit >= jiffies); i++)
>  		inw(REG(PSS_CONTROL));
>  	outw(0x0000, REG(PSS_CONTROL));
>  	return 1;
> @@ -369,11 +369,11 @@ static int pss_download_boot(pss_confdata * devc, unsigned char *block, int size
>  		outw(0, REG(PSS_DATA));
>  
>  		limit = jiffies + HZ/10;
> -		for (i = 0; i < 32768 && (limit - jiffies >= 0); i++)
> +		for (i = 0; i < 32768 && (limit >= jiffies); i++)
>  			val = inw(REG(PSS_STATUS));
>  
>  		limit = jiffies + HZ/10;
> -		for (i = 0; i < 32768 && (limit-jiffies >= 0); i++)
> +		for (i = 0; i < 32768 && (limit >= jiffies); i++)
>  		{
>  			val = inw(REG(PSS_STATUS));
>  			if (val & 0x4000)
> _______________________________________________
> Alsa-devel mailing list
> Alsa-devel@...a-project.org
> http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
> 

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