[PATCH 3/3] common: console: Fix possible null pointer dereference

[Sascha Hauer]

On Sun, Jul 07, 2013 at 04:27:17PM +0400, Alexander Shiyan wrote:
> 
> Signed-off-by: Alexander Shiyan <shc_work at mail.ru>
> ---
>  common/console.c | 30 +++++++++++++++---------------
>  1 file changed, 15 insertions(+), 15 deletions(-)
> 
> diff --git a/common/console.c b/common/console.c
> index a0a06f6..fc7b9ba 100644
> --- a/common/console.c
> +++ b/common/console.c
> @@ -62,23 +62,23 @@ static int console_std_set(struct device_d *dev, struct param_d *param,
>  	char active[4];
>  	unsigned int flag = 0, i = 0;
>  
> -	if (!val)
> -		dev_param_set_generic(dev, param, NULL);
> -
> -	if (strchr(val, 'i') && cdev->f_caps & CONSOLE_STDIN) {
> -		active[i++] = 'i';
> -		flag |= CONSOLE_STDIN;
> -	}
> +	if (val) {
> +		if (strchr(val, 'i') && cdev->f_caps & CONSOLE_STDIN) {
> +			active[i++] = 'i';
> +			flag |= CONSOLE_STDIN;
> +		}
>  
> -	if (strchr(val, 'o') && cdev->f_caps & CONSOLE_STDOUT) {
> -		active[i++] = 'o';
> -		flag |= CONSOLE_STDOUT;
> -	}
> +		if (strchr(val, 'o') && cdev->f_caps & CONSOLE_STDOUT) {
> +			active[i++] = 'o';
> +			flag |= CONSOLE_STDOUT;
> +		}
>  
> -	if (strchr(val, 'e') && cdev->f_caps & CONSOLE_STDERR) {
> -		active[i++] = 'e';
> -		flag |= CONSOLE_STDERR;
> -	}
> +		if (strchr(val, 'e') && cdev->f_caps & CONSOLE_STDERR) {
> +			active[i++] = 'e';
> +			flag |= CONSOLE_STDERR;
> +		}
> +	} else
> +		dev_param_set_generic(dev, param, NULL);

This is not necessary. dev_param_set_generic is called afterwards again.
Indeed it was very easy to crash barebox by doing a 'cs0.active='. I
changed the patch to the following and applied this series.

Thanks
 Sascha

8<------------------------------------------------

>From 4ccf45db0a5f27b998a5dc7560bfb7a228bf5e96 Mon Sep 17 00:00:00 2001
From: Alexander Shiyan <shc_work at mail.ru>
Date: Sun, 7 Jul 2013 16:27:17 +0400
Subject: [PATCH] common: console: Fix possible null pointer dereference

doing a 'cs0.active=' on the command line crashed barebox. Fix this by
not dereferencing val when it's NULL.

Signed-off-by: Alexander Shiyan <shc_work at mail.ru>
Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
---
 common/console.c | 27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/common/console.c b/common/console.c
index a0a06f6..8a4b224 100644
--- a/common/console.c
+++ b/common/console.c
@@ -62,22 +62,21 @@ static int console_std_set(struct device_d *dev, struct param_d *param,
 	char active[4];
 	unsigned int flag = 0, i = 0;
 
-	if (!val)
-		dev_param_set_generic(dev, param, NULL);
-
-	if (strchr(val, 'i') && cdev->f_caps & CONSOLE_STDIN) {
-		active[i++] = 'i';
-		flag |= CONSOLE_STDIN;
-	}
+	if (val) {
+		if (strchr(val, 'i') && cdev->f_caps & CONSOLE_STDIN) {
+			active[i++] = 'i';
+			flag |= CONSOLE_STDIN;
+		}
 
-	if (strchr(val, 'o') && cdev->f_caps & CONSOLE_STDOUT) {
-		active[i++] = 'o';
-		flag |= CONSOLE_STDOUT;
-	}
+		if (strchr(val, 'o') && cdev->f_caps & CONSOLE_STDOUT) {
+			active[i++] = 'o';
+			flag |= CONSOLE_STDOUT;
+		}
 
-	if (strchr(val, 'e') && cdev->f_caps & CONSOLE_STDERR) {
-		active[i++] = 'e';
-		flag |= CONSOLE_STDERR;
+		if (strchr(val, 'e') && cdev->f_caps & CONSOLE_STDERR) {
+			active[i++] = 'e';
+			flag |= CONSOLE_STDERR;
+		}
 	}
 
 	active[i] = 0;
-- 
1.8.3.2

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