From: Keir Fraser <keir.fraser@citrix.com>
Date: Fri, 14 Dec 2007 11:28:40 +0000 (+0000)
Subject: cpufreq: add bounds checking to cpufreq_stats.c from upstream
X-Git-Tag: xen-3.2.0~46
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=eb709ee510aac194d953b90e97bb2749105c7e96;p=legacy%2Flinux-2.6.18-xen.git

cpufreq: add bounds checking to cpufreq_stats.c from upstream

The cpufreq_stats.c will attempt to use an error return value as
an index to an array, causing the kernel to oops.  Stop that by
doing bounds checking.

This is a backport of upstream code.

Signed-off-by: Mark Langsdorf <mark.langsdorf@amd.com>
---

diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
index c2ecc599..bb2125c6 100644
--- a/drivers/cpufreq/cpufreq_stats.c
+++ b/drivers/cpufreq/cpufreq_stats.c
@@ -292,6 +292,9 @@ cpufreq_stat_notifier_trans (struct notifier_block *nb, unsigned long val,
 	if (old_index == new_index)
 		return 0;
 
+        if ((old_index < 0) || (new_index < 0))
+                return 0;
+
 	spin_lock(&cpufreq_stats_lock);
 	stat->last_index = new_index;
 #ifdef CONFIG_CPU_FREQ_STAT_DETAILS