This reverts commit 5b28dde51d0c ("[media] media: fix use-after-free in
cdev_put() when app exits after driver unbind"). The commit was part of an
original patchset to avoid crashes when an unregistering device is in use.
Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
---
drivers/media/mc/mc-device.c | 6 ++---
drivers/media/mc/mc-devnode.c | 48 ++++++++++++++---------------------
2 files changed, 21 insertions(+), 33 deletions(-)
diff --git a/drivers/media/mc/mc-device.c b/drivers/media/mc/mc-device.c
index 013d54e1a55a..b6640e2c8a4c 100644
--- a/drivers/media/mc/mc-device.c
+++ b/drivers/media/mc/mc-device.c
@@ -736,16 +736,16 @@ int __must_check __media_device_register(struct media_device *mdev,
ret = media_devnode_register(mdev, devnode, owner);
if (ret < 0) {
- /* devnode free is handled in media_devnode_*() */
mdev->devnode = NULL;
+ kfree(devnode);
return ret;
}
ret = device_create_file(&devnode->dev, &dev_attr_model);
if (ret < 0) {
- /* devnode free is handled in media_devnode_*() */
mdev->devnode = NULL;
media_devnode_unregister(devnode);
+ kfree(devnode);
return ret;
}
@@ -829,8 +829,6 @@ void media_device_unregister(struct media_device *mdev)
if (media_devnode_is_registered(mdev->devnode)) {
device_remove_file(&mdev->devnode->dev, &dev_attr_model);
media_devnode_unregister(mdev->devnode);
- /* devnode free is handled in media_devnode_*() */
- mdev->devnode = NULL;
}
}
EXPORT_SYMBOL_GPL(media_device_unregister);
diff --git a/drivers/media/mc/mc-devnode.c b/drivers/media/mc/mc-devnode.c
index 740573552e5d..1e1792c3ae3f 100644
--- a/drivers/media/mc/mc-devnode.c
+++ b/drivers/media/mc/mc-devnode.c
@@ -51,8 +51,13 @@ static void media_devnode_release(struct device *cd)
struct media_devnode *devnode = to_media_devnode(cd);
mutex_lock(&media_devnode_lock);
+
+ /* Delete the cdev on this minor as well */
+ cdev_del(&devnode->cdev);
+
/* Mark device node number as free */
clear_bit(devnode->minor, media_devnode_nums);
+
mutex_unlock(&media_devnode_lock);
/* Release media_devnode and perform other cleanups as needed. */
@@ -60,7 +65,6 @@ static void media_devnode_release(struct device *cd)
devnode->release(devnode);
kfree(devnode);
- pr_debug("%s: Media Devnode Deallocated\n", __func__);
}
static struct bus_type media_bus_type = {
@@ -189,8 +193,6 @@ static int media_release(struct inode *inode, struct file *filp)
/* decrease the refcount unconditionally since the release()
return value is ignored. */
put_device(&devnode->dev);
-
- pr_debug("%s: Media Release\n", __func__);
return 0;
}
@@ -221,7 +223,6 @@ int __must_check media_devnode_register(struct media_device *mdev,
if (minor == MEDIA_NUM_DEVICES) {
mutex_unlock(&media_devnode_lock);
pr_err("could not get a free minor\n");
- kfree(devnode);
return -ENFILE;
}
@@ -231,33 +232,29 @@ int __must_check media_devnode_register(struct media_device *mdev,
devnode->minor = minor;
devnode->media_dev = mdev;
- /* Part 1: Initialize dev now to use dev.kobj for cdev.kobj.parent */
- devnode->dev.bus = &media_bus_type;
- devnode->dev.devt = MKDEV(MAJOR(media_dev_t), devnode->minor);
- devnode->dev.release = media_devnode_release;
- if (devnode->parent)
- devnode->dev.parent = devnode->parent;
- dev_set_name(&devnode->dev, "media%d", devnode->minor);
- device_initialize(&devnode->dev);
-
/* Part 2: Initialize and register the character device */
cdev_init(&devnode->cdev, &media_devnode_fops);
devnode->cdev.owner = owner;
- devnode->cdev.kobj.parent = &devnode->dev.kobj;
kobject_set_name(&devnode->cdev.kobj, "media%d", devnode->minor);
ret = cdev_add(&devnode->cdev, MKDEV(MAJOR(media_dev_t),
devnode->minor), 1);
if (ret < 0) {
pr_err("%s: cdev_add failed\n", __func__);
- goto cdev_add_error;
+ goto error;
}
- /* Part 3: Add the media device */
- ret = device_add(&devnode->dev);
+ /* Part 3: Register the media device */
+ devnode->dev.bus = &media_bus_type;
+ devnode->dev.devt = MKDEV(MAJOR(media_dev_t), devnode->minor);
+ devnode->dev.release = media_devnode_release;
+ if (devnode->parent)
+ devnode->dev.parent = devnode->parent;
+ dev_set_name(&devnode->dev, "media%d", devnode->minor);
+ ret = device_register(&devnode->dev);
if (ret < 0) {
- pr_err("%s: device_add failed\n", __func__);
- goto device_add_error;
+ pr_err("%s: device_register failed\n", __func__);
+ goto error;
}
/* Part 4: Activate this minor. The char device can now be used. */
@@ -265,15 +262,12 @@ int __must_check media_devnode_register(struct media_device *mdev,
return 0;
-device_add_error:
- cdev_del(&devnode->cdev);
-cdev_add_error:
+error:
mutex_lock(&media_devnode_lock);
+ cdev_del(&devnode->cdev);
clear_bit(devnode->minor, media_devnode_nums);
- devnode->media_dev = NULL;
mutex_unlock(&media_devnode_lock);
- put_device(&devnode->dev);
return ret;
}
@@ -285,13 +279,9 @@ void media_devnode_unregister(struct media_devnode *devnode)
mutex_lock(&media_devnode_lock);
clear_bit(MEDIA_FLAG_REGISTERED, &devnode->flags);
- /* Delete the cdev on this minor as well */
- cdev_del(&devnode->cdev);
- devnode->media_dev = NULL;
mutex_unlock(&media_devnode_lock);
- device_del(&devnode->dev);
- put_device(&devnode->dev);
+ device_unregister(&devnode->dev);
}
/*
--
2.30.2
