linux-kernel - [PATCH 2/5] power: supply: max17040: handle device_property_read_u8

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Message-Id: <20210419163336.64075-2-krzysztof.kozlowski@canonical.com>
Date:   Mon, 19 Apr 2021 18:33:33 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
To:     Sebastian Reichel <sre@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/5] power: supply: max17040: handle device_property_read_u8_array() failure

The device_property_read_u8_array() call should not fail because it is
preceded with device_property_count_u8() and check for number of
readable u8 values.  However the code is more obvious and easier to read
if the return value of device_property_read_u8_array() is checked.
Otherwise reader needs to investigate whether really there is no risk of
using random stack values of 'rcomp' variable.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
---
 drivers/power/supply/max17040_battery.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/power/supply/max17040_battery.c b/drivers/power/supply/max17040_battery.c
index d956c67d5155..d2053cd0bd13 100644
--- a/drivers/power/supply/max17040_battery.c
+++ b/drivers/power/supply/max17040_battery.c
@@ -268,11 +268,10 @@ static int max17040_get_of_data(struct max17040_chip *chip)
 	rcomp_len = device_property_count_u8(dev, "maxim,rcomp");
 	chip->rcomp = MAX17040_RCOMP_DEFAULT;
 	if (rcomp_len == data->rcomp_bytes) {
-		device_property_read_u8_array(dev, "maxim,rcomp",
-					      rcomp, rcomp_len);
-		chip->rcomp = rcomp_len == 2 ?
-			rcomp[0] << 8 | rcomp[1] :
-			rcomp[0] << 8;
+		if (!device_property_read_u8_array(dev, "maxim,rcomp",
+						   rcomp, rcomp_len))
+			chip->rcomp = rcomp_len == 2 ? rcomp[0] << 8 | rcomp[1] :
+				      rcomp[0] << 8;
 	} else if (rcomp_len > 0) {
 		dev_err(dev, "maxim,rcomp has incorrect length\n");
 		return -EINVAL;
-- 
2.25.1