[PATCH v2 0/2] driver core: faux: fix root device registration

[PATCH v2 0/2] driver core: faux: fix root device registration

[Johan Hovold]

This series fixes the faux bus root device registration by using
root_device_register().

Included is also a related cleanup.

Johan


Changes in v2:
 - only set the faux_bus_root pointer on successful registration
 - clean up the init error handling


Johan Hovold (2):
  driver core: faux: fix root device registration
  driver core: faux: clean up init error handling

 drivers/base/faux.c | 32 +++++++++++++++-----------------
 1 file changed, 15 insertions(+), 17 deletions(-)

-- 
2.53.0

[PATCH v2 1/2] driver core: faux: fix root device registration

[Johan Hovold]

A recent change made the faux bus root device be allocated dynamically
but failed to provide a release function to free the memory when the
last reference is dropped (on theoretical failure to register the device
or bus).

Fix this by using root_device_register() instead of open coding.

Also add the missing sanity check when registering faux devices to avoid
use-after-free if the bus failed to register (which would previously
have triggered a bunch of use-after-free warnings).

Fixes: 61b76d07d2b4 ("driver core: faux: stop using static struct device")
Cc: stable@vger.kernel.org	# 7.0
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/base/faux.c | 22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/drivers/base/faux.c b/drivers/base/faux.c
index fb3e42f21362..3d1d1eafb473 100644
--- a/drivers/base/faux.c
+++ b/drivers/base/faux.c
@@ -133,6 +133,9 @@ struct faux_device *faux_device_create_with_groups(const char *name,
 	struct device *dev;
 	int ret;
 
+	if (!faux_bus_root)
+		return NULL;
+
 	faux_obj = kzalloc_obj(*faux_obj);
 	if (!faux_obj)
 		return NULL;
@@ -232,19 +235,12 @@ EXPORT_SYMBOL_GPL(faux_device_destroy);
 
 int __init faux_bus_init(void)
 {
+	struct device *root;
 	int ret;
 
-	faux_bus_root = kzalloc_obj(*faux_bus_root);
-	if (!faux_bus_root)
-		return -ENOMEM;
-
-	dev_set_name(faux_bus_root, "faux");
-
-	ret = device_register(faux_bus_root);
-	if (ret) {
-		put_device(faux_bus_root);
-		return ret;
-	}
+	root = root_device_register("faux");
+	if (IS_ERR(root))
+		return PTR_ERR(root);
 
 	ret = bus_register(&faux_bus_type);
 	if (ret)
@@ -254,12 +250,14 @@ int __init faux_bus_init(void)
 	if (ret)
 		goto error_driver;
 
+	faux_bus_root = root;
+
 	return ret;
 
 error_driver:
 	bus_unregister(&faux_bus_type);
 
 error_bus:
-	device_unregister(faux_bus_root);
+	root_device_unregister(root);
 	return ret;
 }
-- 
2.53.0

[PATCH v2 2/2] driver core: faux: clean up init error handling

[Johan Hovold]

Clean up the faux bus init error handling by naming the labels after
what they do (rather than from where they are jumped to) and separating
the success path more clearly by returning explicit zero.

Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/base/faux.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/base/faux.c b/drivers/base/faux.c
index 3d1d1eafb473..a8329f88222e 100644
--- a/drivers/base/faux.c
+++ b/drivers/base/faux.c
@@ -244,20 +244,20 @@ int __init faux_bus_init(void)
 
 	ret = bus_register(&faux_bus_type);
 	if (ret)
-		goto error_bus;
+		goto err_deregister_root;
 
 	ret = driver_register(&faux_driver);
 	if (ret)
-		goto error_driver;
+		goto err_deregister_bus;
 
 	faux_bus_root = root;
 
-	return ret;
+	return 0;
 
-error_driver:
+err_deregister_bus:
 	bus_unregister(&faux_bus_type);
-
-error_bus:
+err_deregister_root:
 	root_device_unregister(root);
+
 	return ret;
 }
-- 
2.53.0