From 8302532f47bb6c3aa1ed2043d30187ca307f176a Mon Sep 17 00:00:00 2001
From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Date: Fri, 4 Feb 2022 17:59:20 +0200
Subject: [PATCH] i2c: smbus: Check for parent device before dereference
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Git-commit: 8302532f47bb6c3aa1ed2043d30187ca307f176a
Patch-mainline: v5.18-rc1
References: git-fixes

An I²C adapter might be instantiated without parent. In such case
there is no property can be retrieved. Skip SMBus alert setup when
this happens.

Fixes: a263a84088f6 ("i2c: smbus: Use device_*() functions instead of of_*()")
Reported-by: syzbot+0591ccf54ee05344e4eb@syzkaller.appspotmail.com
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/i2c/i2c-core-smbus.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c
index 053b215308c4..e3b96fc53b5c 100644
--- a/drivers/i2c/i2c-core-smbus.c
+++ b/drivers/i2c/i2c-core-smbus.c
@@ -705,10 +705,14 @@ EXPORT_SYMBOL_GPL(i2c_new_smbus_alert_device);
 #if IS_ENABLED(CONFIG_I2C_SMBUS)
 int i2c_setup_smbus_alert(struct i2c_adapter *adapter)
 {
+	struct device *parent = adapter->dev.parent;
 	int irq;
 
-	irq = device_property_match_string(adapter->dev.parent, "interrupt-names",
-					   "smbus_alert");
+	/* Adapter instantiated without parent, skip the SMBus alert setup */
+	if (!parent)
+		return 0;
+
+	irq = device_property_match_string(parent, "interrupt-names", "smbus_alert");
 	if (irq == -EINVAL || irq == -ENODATA)
 		return 0;
 	else if (irq < 0)
-- 
2.35.3