linux-kernel - [PATCH v1] device property: Avoid NULL pointer dereference in device_get_next_child

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Date:   Thu, 16 Jul 2020 21:27:47 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        linux-kernel@...r.kernel.org
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Maxim Levitsky <mlevitsk@...hat.com>
Subject: [PATCH v1] device property: Avoid NULL pointer dereference in device_get_next_child_node()

When we have no primary fwnode or when it's a software node, we may end up
in the situation when fwnode is a NULL pointer. There is no point to look for
secondary fwnode in such case. Add a necessary check to a condition.

Fixes: 114dbb4fa7c4 ("drivers property: When no children in primary, try secondary")
Reported-by: Maxim Levitsky <mlevitsk@...hat.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---
 drivers/base/property.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/base/property.c b/drivers/base/property.c
index 1e6d75e65938..d58aa98fe964 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c
@@ -721,7 +721,7 @@ struct fwnode_handle *device_get_next_child_node(struct device *dev,
 		return next;
 
 	/* When no more children in primary, continue with secondary */
-	if (!IS_ERR_OR_NULL(fwnode->secondary))
+	if (fwnode && !IS_ERR_OR_NULL(fwnode->secondary))
 		next = fwnode_get_next_child_node(fwnode->secondary, child);
 
 	return next;
-- 
2.27.0