[PATCH 6.1.y 4/5] i2c: core: fix NULL-deref on adapter registration failure

[Sasha Levin <sashal@kernel.org>]

From: Johan Hovold <johan@kernel.org>

[ Upstream commit 2295d2bb101faa663fbc45fadbb3fec45f107441 ]

If adapter registration ever fails the release callback would trigger a
NULL-pointer dereference as the completion struct has not been
initialised.

Note that before the offending commit this would instead have resulted
in a minor memory leak of the adapter name.

Fixes: 3f8c4f5e9a57 ("i2c: core: fix reference leak in i2c_register_adapter()")
Cc: stable@vger.kernel.org
Cc: Joe Hattori <joe@pf.is.s.u-tokyo.ac.jp>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Stable-dep-of: 158efa411c57 ("i2c: core: fix adapter probe deferral loop")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/i2c/i2c-core-base.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index df2ded29788d1d..e82607643ebfb4 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -1567,8 +1567,7 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
 	res = device_add(&adap->dev);
 	if (res) {
 		pr_err("adapter '%s': can't register device (%d)\n", adap->name, res);
-		put_device(&adap->dev);
-		goto err_remove_irq_domain;
+		goto err_put_adap;
 	}
 
 	adap->debugfs = debugfs_create_dir(dev_name(&adap->dev), i2c_debugfs_root);
@@ -1608,10 +1607,12 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
 
 out_reg:
 	debugfs_remove_recursive(adap->debugfs);
+	device_del(&adap->dev);
+err_put_adap:
 	init_completion(&adap->dev_released);
-	device_unregister(&adap->dev);
+	put_device(&adap->dev);
 	wait_for_completion(&adap->dev_released);
-err_remove_irq_domain:
+
 	i2c_host_notify_irq_teardown(adap);
 out_list:
 	mutex_lock(&core_lock);
-- 
2.53.0