[PATCH] sched: fix strncmp operation

[PATCH] sched: fix strncmp operation

[Hillf Danton]

One of the operands, buf, is incorrect, since it is stripped and the
correct address for subsequent string comparing could change if
leading white spaces, if any, are removed from buf.

It is fixed by replacing buf with cmp.

Signed-off-by: Hillf Danton <dhillf@gmail.com>
---

--- a/kernel/sched.c	2010-11-01 19:54:12.000000000 +0800
+++ b/kernel/sched.c	2011-01-06 20:52:02.000000000 +0800
@@ -751,7 +751,7 @@ sched_feat_write(struct file *filp, cons
 	buf[cnt] = 0;
 	cmp = strstrip(buf);

-	if (strncmp(buf, "NO_", 3) == 0) {
+	if (strncmp(cmp, "NO_", 3) == 0) {
 		neg = 1;
 		cmp += 3;
 	}

Re: [PATCH] sched: fix strncmp operation

[Andrew Morton]

On Thu, 6 Jan 2011 20:58:12 +0800
Hillf Danton <dhillf@gmail.com> wrote:

> One of the operands, buf, is incorrect, since it is stripped and the
> correct address for subsequent string comparing could change if
> leading white spaces, if any, are removed from buf.
> 
> It is fixed by replacing buf with cmp.
> 
> Signed-off-by: Hillf Danton <dhillf@gmail.com>
> ---
> 
> --- a/kernel/sched.c	2010-11-01 19:54:12.000000000 +0800
> +++ b/kernel/sched.c	2011-01-06 20:52:02.000000000 +0800
> @@ -751,7 +751,7 @@ sched_feat_write(struct file *filp, cons
>  	buf[cnt] = 0;
>  	cmp = strstrip(buf);
> 
> -	if (strncmp(buf, "NO_", 3) == 0) {
> +	if (strncmp(cmp, "NO_", 3) == 0) {
>  		neg = 1;
>  		cmp += 3;
>  	}

Just remove the strstrip(), I'd say.  The kernel practically never
strips leading whitespace from sysfs input, so why do it here? 

Re: [PATCH] sched: fix strncmp operation

[Hillf Danton]

On Fri, Jan 7, 2011 at 7:47 AM, Andrew Morton <akpm@linux-foundation.org> wrote:
> Just remove the strstrip(), I'd say.  The kernel practically never
> strips leading whitespace from sysfs input, so why do it here?
>

Would you please, Andrew, take another glance at the patch for
replacing ida in workqueue?

              https://lkml.org/lkml/2010/12/18/35

thanks
Hillf

[tip:sched/urgent] sched: Fix strncmp operation

[tip-bot for Hillf Danton]

Commit-ID:  524429c31b486c05449666b94613f59f729c0a84
Gitweb:     http://git.kernel.org/tip/524429c31b486c05449666b94613f59f729c0a84
Author:     Hillf Danton <dhillf@gmail.com>
AuthorDate: Thu, 6 Jan 2011 20:58:12 +0800
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Fri, 7 Jan 2011 15:55:10 +0100

sched: Fix strncmp operation

One of the operands, buf, is incorrect, since it is stripped and the
correct address for subsequent string comparing could change if
leading white spaces, if any, are removed from buf.

It is fixed by replacing buf with cmp.

Signed-off-by: Hillf Danton <dhillf@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <AANLkTinOPuYsVovrZpbuCCmG5deEyc8WgA_A1RJx_YK7@mail.gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 kernel/sched.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index a8478a2..a0eb094 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -741,7 +741,7 @@ sched_feat_write(struct file *filp, const char __user *ubuf,
 	buf[cnt] = 0;
 	cmp = strstrip(buf);
 
-	if (strncmp(buf, "NO_", 3) == 0) {
+	if (strncmp(cmp, "NO_", 3) == 0) {
 		neg = 1;
 		cmp += 3;
 	}