linux-kernel - [PATCH] mfd: mc13xxx: fix a missing check of a register-read failure

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Message-Id: <20181220211211.32608-1-kjlu@umn.edu>
Date:   Thu, 20 Dec 2018 15:12:11 -0600
From:   Kangjie Lu <kjlu@....edu>
To:     kjlu@....edu
Cc:     pakki001@....edu, Lee Jones <lee.jones@...aro.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] mfd: mc13xxx: fix a missing check of a register-read failure

When mc13xxx_reg_read() fails, "old_adc0" is uninitialized and will
contain random value. Further execution uses "old_adc0" even when
mc13xxx_reg_read() fails.
The fix checks the return value of mc13xxx_reg_read(), and exits
the execution when it fails.

Signed-off-by: Kangjie Lu <kjlu@....edu>
---
 drivers/mfd/mc13xxx-core.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/mfd/mc13xxx-core.c b/drivers/mfd/mc13xxx-core.c
index f475e848252f..d0bf50e3568d 100644
--- a/drivers/mfd/mc13xxx-core.c
+++ b/drivers/mfd/mc13xxx-core.c
@@ -274,7 +274,9 @@ int mc13xxx_adc_do_conversion(struct mc13xxx *mc13xxx, unsigned int mode,
 
 	mc13xxx->adcflags |= MC13XXX_ADC_WORKING;
 
-	mc13xxx_reg_read(mc13xxx, MC13XXX_ADC0, &old_adc0);
+	ret = mc13xxx_reg_read(mc13xxx, MC13XXX_ADC0, &old_adc0);
+	if (ret)
+		goto out;
 
 	adc0 = MC13XXX_ADC0_ADINC1 | MC13XXX_ADC0_ADINC2 |
 	       MC13XXX_ADC0_CHRGRAWDIV;
-- 
2.17.1