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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Kangjie Lu <kjlu@umn.edu>,
        Lee Jones <lee.jones@linaro.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.20 038/183] mfd: mc13xxx: Fix a missing check of a register-read failure
Date:   Mon, 25 Feb 2019 22:10:11 +0100
Message-Id: <20190225195101.078229480@linuxfoundation.org>
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4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit 9e28989d41c0eab57ec0bb156617a8757406ff8a ]

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@umn.edu>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 f475e848252fa..d0bf50e3568d7 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;
-- 
2.19.1