linux-kernel - [PATCH v2] extcon: palmas: Check the parent instance to prevent the NULL

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Date:   Thu, 8 Dec 2016 10:45:31 +0200
From:   Roger Quadros <rogerq@...com>
To:     <cw00.choi@...sung.com>, <myungjoo.ham@...sung.com>
CC:     <linux-kernel@...r.kernel.org>, <rogerq@...com>
Subject: [PATCH v2] extcon: palmas: Check the parent instance to prevent the
 NULL

extcon-palmas must be child of palmas and expects parent's
drvdata to be valid. Check for non NULL parent drvdata and
fail if it is NULL. Not doing so will result in a NULL
pointer dereference later in the probe() parent drvdata
is NULL (e.g. misplaced extcon-palmas node in device tree).

Signed-off-by: Roger Quadros <rogerq@...com>
---
Changelog:
v2:
- updated error message and commit message subject

 drivers/extcon/extcon-palmas.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/extcon/extcon-palmas.c b/drivers/extcon/extcon-palmas.c
index 634ba70..a128fd2 100644
--- a/drivers/extcon/extcon-palmas.c
+++ b/drivers/extcon/extcon-palmas.c
@@ -190,6 +190,11 @@ static int palmas_usb_probe(struct platform_device *pdev)
 	struct palmas_usb *palmas_usb;
 	int status;
 
+	if (!palmas) {
+		dev_err(&pdev->dev, "failed to get valid parent\n");
+		return -EINVAL;
+	}
+
 	palmas_usb = devm_kzalloc(&pdev->dev, sizeof(*palmas_usb), GFP_KERNEL);
 	if (!palmas_usb)
 		return -ENOMEM;
-- 
2.7.4