i2c: smbus: Check for parent device before dereference

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>

diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c
index 053b215..e3b96fc 100644 (file)
--- 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)