linux-kernel - [PATCH v2] backlight: mp3309c: fix uninitialized local variable

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Date:   Wed, 29 Nov 2023 17:45:14 +0100
From:   Flavio Suligoi <f.suligoi@...m.it>
To:     Lee Jones <lee@...nel.org>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Jingoo Han <jingoohan1@...il.com>,
        Helge Deller <deller@....de>,
        Dan Carpenter <dan.carpenter@...aro.org>
Cc:     dri-devel@...ts.freedesktop.org, linux-fbdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Flavio Suligoi <f.suligoi@...m.it>
Subject: [PATCH v2] backlight: mp3309c: fix uninitialized local variable

In the function "pm3309c_parse_dt_node", when the dimming analog control
mode (by I2C messages) is enabled, the local variable "prop_levels" is
tested without any initialization, as indicated by the following smatch
warning:

drivers/video/backlight/mp3309c.c:279 pm3309c_parse_dt_node() error: uninitialized symbol 'prop_levels'.

To avoid any problem in case of undefined behavior, we need to initialize
it to "NULL".

Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
Closes: https://lore.kernel.org/dri-devel/af0a1870-693b-442f-9b11-0503cfcd944a@moroto.mountain/
Fixes: 2e914516a58c ("backlight: mp3309c: Add support for MPS MP3309C")
Signed-off-by: Flavio Suligoi <f.suligoi@...m.it>
---

v2:
 - remove redundant initialization of "prop_pwms" variable
 - remove "thanks to Dan Carpenter for the report"
 - add "Reported-by: Dan Carpenter <dan.carpenter@...aro.org>" tag
 - add "Closes:" tag

 drivers/video/backlight/mp3309c.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/video/backlight/mp3309c.c b/drivers/video/backlight/mp3309c.c
index 3fe4469ef43f..34d71259fac1 100644
--- a/drivers/video/backlight/mp3309c.c
+++ b/drivers/video/backlight/mp3309c.c
@@ -203,7 +203,8 @@ static int pm3309c_parse_dt_node(struct mp3309c_chip *chip,
 				 struct mp3309c_platform_data *pdata)
 {
 	struct device_node *node = chip->dev->of_node;
-	struct property *prop_pwms, *prop_levels;
+	struct property *prop_pwms;
+	struct property *prop_levels = NULL;
 	int length = 0;
 	int ret, i;
 	unsigned int num_levels, tmp_value;
-- 
2.34.1