linux-kernel - [PATCH] [CPUFREQ] EXYNOS: bugfix on retrieving old

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 04 Apr 2012 19:23:56 +0900
From:	MyungJoo Ham <myungjoo.ham@...sung.com>
To:	cpufreq@...r.kernel.org
Cc:	Dave Jones <davej@...hat.com>, Jaecheol Lee <jc.lee@...sung.com>,
	Tushar Behera <tushar.behera@...aro.org>,
	kyungmin.park@...sung.com, cw00.choi@...sung.com,
	myungjoo.ham@...il.com, linux-kernel@...r.kernel.org
Subject: [PATCH] [CPUFREQ] EXYNOS: bugfix on retrieving old_index from freqs.old

The policy might have been changed since last call of target().
Thus, using cpufreq_frequency_table_target(), which depends on
policy to find the correspoding index from a frequency, may return
inconsistent index for freqs.old. Thus, old_index should be
calculated not based on the current policy.

We have been observing such issue when scaling_min/max_freq were
updated and sometimes caused system lockups due to incorrectly
configured voltages.

Signed-off-by: MyungJoo Ham <myungjoo.ham@...sung.com>
---
 drivers/cpufreq/exynos-cpufreq.c |   13 +++++++++++--
 1 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/cpufreq/exynos-cpufreq.c b/drivers/cpufreq/exynos-cpufreq.c
index b243a7e..1577522 100644
--- a/drivers/cpufreq/exynos-cpufreq.c
+++ b/drivers/cpufreq/exynos-cpufreq.c
@@ -62,8 +62,17 @@ static int exynos_target(struct cpufreq_policy *policy,
 		goto out;
 	}
 
-	if (cpufreq_frequency_table_target(policy, freq_table,
-					   freqs.old, relation, &old_index)) {
+	/*
+	 * The policy may have been changed so that we cannot get proper
+	 * old_index with cpufreq_frequency_table_target(). Thus, ignore
+	 * policy and get the index from the raw frequency table.
+	 */
+	for (old_index = 0;
+	     freq_table[old_index].frequency != CPUFREQ_TABLE_END;
+	     old_index++)
+		if (freq_table[old_index].frequency == freqs.old)
+			break;
+	if (freq_table[old_index].frequency == CPUFREQ_TABLE_END) {
 		ret = -EINVAL;
 		goto out;
 	}
-- 
1.7.4.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/