[2.6 patch] iwl4965-base.c: fix off-by-one errors

[2.6 patch] iwl4965-base.c: fix off-by-one errors

[Adrian Bunk]

This patch fixes two off-by-one errors resulting in array overflows 
spotted by the Coverity checker.

Signed-off-by: Adrian Bunk <bunk@kernel.org>

---

 drivers/net/wireless/iwlwifi/iwl4965-base.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- linux-2.6/drivers/net/wireless/iwlwifi/iwl4965-base.c.old	2007-10-14 16:52:21.000000000 +0200
+++ linux-2.6/drivers/net/wireless/iwlwifi/iwl4965-base.c	2007-10-14 16:59:37.000000000 +0200
@@ -4489,23 +4489,23 @@ static u8 ratio2dB[100] = {
 	39, 39, 39, 39, 39, 40, 40, 40, 40, 40  /* 90 - 99 */
 };
 
 /* Calculates a relative dB value from a ratio of linear
  *   (i.e. not dB) signal levels.
  * Conversion assumes that levels are voltages (20*log), not powers (10*log). */
 int iwl_calc_db_from_ratio(int sig_ratio)
 {
-	/* Anything above 1000:1 just report as 60 dB */
-	if (sig_ratio > 1000)
+	/* 1000:1 or higher just report as 60 dB */
+	if (sig_ratio >= 1000)
 		return 60;
 
-	/* Above 100:1, divide by 10 and use table,
+	/* 100:1 or higher, divide by 10 and use table,
 	 *   add 20 dB to make up for divide by 10 */
-	if (sig_ratio > 100)
+	if (sig_ratio >= 100)
 		return (20 + (int)ratio2dB[sig_ratio/10]);
 
 	/* We shouldn't see this */
 	if (sig_ratio < 1)
 		return 0;
 
 	/* Use table for ratios 1:1 - 99:1 */
 	return (int)ratio2dB[sig_ratio];

Re: [2.6 patch] iwl4965-base.c: fix off-by-one errors

[Zhu Yi]

On Sun, 2007-10-14 at 19:51 +0200, Adrian Bunk wrote:
> This patch fixes two off-by-one errors resulting in array overflows 
> spotted by the Coverity checker.
> 
> Signed-off-by: Adrian Bunk <bunk@kernel.org>

ACK.

John, please apply.

Thanks,
-yi

RE: [2.6 patch] iwl4965-base.c: fix off-by-one errors

[Cahill, Ben M]

ACK ... good catch.

-- Ben --

> -----Original Message-----
> From: linux-wireless-owner@vger.kernel.org 
> [mailto:linux-wireless-owner@vger.kernel.org] On Behalf Of Adrian Bunk
> Sent: Sunday, October 14, 2007 1:51 PM
> To: Zhu, Yi
> Cc: linux-wireless@vger.kernel.org; 
> ipw3945-devel@lists.sourceforge.net; linux-kernel@vger.kernel.org
> Subject: [2.6 patch] iwl4965-base.c: fix off-by-one errors
> 
> This patch fixes two off-by-one errors resulting in array 
> overflows spotted by the Coverity checker.
> 
> Signed-off-by: Adrian Bunk <bunk@kernel.org>
> 
> ---
> 
>  drivers/net/wireless/iwlwifi/iwl4965-base.c |    8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> --- linux-2.6/drivers/net/wireless/iwlwifi/iwl4965-base.c.old	
> 2007-10-14 16:52:21.000000000 +0200
> +++ linux-2.6/drivers/net/wireless/iwlwifi/iwl4965-base.c	
> 2007-10-14 16:59:37.000000000 +0200
> @@ -4489,23 +4489,23 @@ static u8 ratio2dB[100] = {
>  	39, 39, 39, 39, 39, 40, 40, 40, 40, 40  /* 90 - 99 */  };
>  
>  /* Calculates a relative dB value from a ratio of linear
>   *   (i.e. not dB) signal levels.
>   * Conversion assumes that levels are voltages (20*log), not 
> powers (10*log). */  int iwl_calc_db_from_ratio(int sig_ratio)  {
> -	/* Anything above 1000:1 just report as 60 dB */
> -	if (sig_ratio > 1000)
> +	/* 1000:1 or higher just report as 60 dB */
> +	if (sig_ratio >= 1000)
>  		return 60;
>  
> -	/* Above 100:1, divide by 10 and use table,
> +	/* 100:1 or higher, divide by 10 and use table,
>  	 *   add 20 dB to make up for divide by 10 */
> -	if (sig_ratio > 100)
> +	if (sig_ratio >= 100)
>  		return (20 + (int)ratio2dB[sig_ratio/10]);
>  
>  	/* We shouldn't see this */
>  	if (sig_ratio < 1)
>  		return 0;
>  
>  	/* Use table for ratios 1:1 - 99:1 */
>  	return (int)ratio2dB[sig_ratio];
> 
> -
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