linux-kernel - [PATCH] PM / OPP: fix off-by-one bug in dev_pm_opp_get_max_volt

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Message-id: <1487617077-21865-1-git-send-email-a.hajda@samsung.com>
Date:   Mon, 20 Feb 2017 19:57:57 +0100
From:   Andrzej Hajda <a.hajda@...sung.com>
To:     Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Andrzej Hajda <a.hajda@...sung.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>
Subject: [PATCH] PM / OPP: fix off-by-one bug in
 dev_pm_opp_get_max_volt_latency loop

Reading array at given index before checking if index is valid results in
illegal memory access.

The bug was detected using KASAN framework.

Signed-off-by: Andrzej Hajda <a.hajda@...sung.com>
---
 drivers/base/power/opp/core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/base/power/opp/core.c b/drivers/base/power/opp/core.c
index 91ec323..dae6172 100644
--- a/drivers/base/power/opp/core.c
+++ b/drivers/base/power/opp/core.c
@@ -231,7 +231,8 @@ unsigned long dev_pm_opp_get_max_volt_latency(struct device *dev)
 	 * The caller needs to ensure that opp_table (and hence the regulator)
 	 * isn't freed, while we are executing this routine.
 	 */
-	for (i = 0; reg = regulators[i], i < count; i++) {
+	for (i = 0; i < count; i++) {
+		reg = regulators[i];
 		ret = regulator_set_voltage_time(reg, uV[i].min, uV[i].max);
 		if (ret > 0)
 			latency_ns += ret * 1000;
-- 
2.7.4