[PATCH 4.9 14/63] mfd: mc13xxx: Fix a missing check of a register-read failure

[Greg Kroah-Hartman]

4.9-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@xxxxxxx>
Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 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 d7f54e492aa61..6c16f170529f5 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;
 	adc1 = MC13XXX_ADC1_ADEN | MC13XXX_ADC1_ADTRIGIGN | MC13XXX_ADC1_ASC;
-- 
2.19.1