linux-kernel - Re: [PATCH] sched: fix string comparison in features

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Date:	Mon, 13 Sep 2010 17:34:32 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...e.hu>, Tony Lindgren <tony@...mide.com>
Subject: Re: [PATCH] sched: fix string comparison in features

On Sat, 2010-09-11 at 13:44 -0400, Mathieu Desnoyers wrote:
> Incorrect handling of the following case:
> 
> INTERACTIVE
> INTERACTIVE_SOMETHING_ELSE
> 
> The comparison only checks up to each element's length.

Replace all your changes with mine, and you have the same effect ;-)

-- Steve

> 
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
> ---
>  kernel/sched.c |   11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> Index: linux-2.6-lttng.git/kernel/sched.c
> ===================================================================
> --- linux-2.6-lttng.git.orig/kernel/sched.c
> +++ linux-2.6-lttng.git/kernel/sched.c
> @@ -722,7 +722,7 @@ sched_feat_write(struct file *filp, cons
>  {
>  	char buf[64];
>  	char *cmp = buf;

-	char *cmp = buf;
+	char *cmp;

> -	int neg = 0;
> +	int neg = 0, cmplen;
>  	int i;
>  
>  	if (cnt > 63)
> @@ -732,15 +732,24 @@ sched_feat_write(struct file *filp, cons
>  		return -EFAULT;
>  
>  	buf[cnt] = 0;
> +	for (i = 0; i < cnt; i++) {
> +		if (buf[i] == '\n' || buf[i] == ' ') {
> +			buf[i] = 0;
> +			break;
> +		}
> +	}

+	cmp = strstrip(buf);

>  
>  	if (strncmp(buf, "NO_", 3) == 0) {
>  		neg = 1;
>  		cmp += 3;
>  	}
>  
> +	cmplen = strlen(cmp);
>  	for (i = 0; sched_feat_names[i]; i++) {
>  		int len = strlen(sched_feat_names[i]);

-		int len = strlen(sched_feat_names[i]);

>  
> +		if (cmplen != len)
> +			continue;
>  		if (strncmp(cmp, sched_feat_names[i], len) == 0) {

-		if (strncmp(cmp, sched_feat_names[i], len) == 0) {
+		if (strcmp(cmp, sched_feat_names[i]) == 0) {

>  			if (neg)
>  				sysctl_sched_features &= ~(1UL << i);


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