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

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Date:	Sat, 11 Sep 2010 13:44:00 -0400
From:	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To:	LKML <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>
Cc:	Ingo Molnar <mingo@...e.hu>, Steven Rostedt <rostedt@...dmis.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Tony Lindgren <tony@...mide.com>
Subject: [PATCH] sched: fix string comparison in features

Incorrect handling of the following case:

INTERACTIVE
INTERACTIVE_SOMETHING_ELSE

The comparison only checks up to each element's length.

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;
-	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;
+		}
+	}
 
 	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]);
 
+		if (cmplen != len)
+			continue;
 		if (strncmp(cmp, sched_feat_names[i], len) == 0) {
 			if (neg)
 				sysctl_sched_features &= ~(1UL << i);
-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com
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