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Subject[PATCH 4.4 015/105] driver core: Dont ignore class_dir_create_and_add() failure.
Date
4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>

commit 84d0c27d6233a9ba0578b20f5a09701eb66cee42 upstream.

syzbot is hitting WARN() at kernfs_add_one() [1].
This is because kernfs_create_link() is confused by previous device_add()
call which continued without setting dev->kobj.parent field when
get_device_parent() failed by memory allocation fault injection.
Fix this by propagating the error from class_dir_create_and_add() to
the calllers of get_device_parent().

[1] https://syzkaller.appspot.com/bug?id=fae0fb607989ea744526d1c082a5b8de6529116f

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-by: syzbot <syzbot+df47f81c226b31d89fb1@syzkaller.appspotmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/base/core.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)

--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -759,7 +759,7 @@ class_dir_create_and_add(struct class *c

dir = kzalloc(sizeof(*dir), GFP_KERNEL);
if (!dir)
- return NULL;
+ return ERR_PTR(-ENOMEM);

dir->class = class;
kobject_init(&dir->kobj, &class_dir_ktype);
@@ -769,7 +769,7 @@ class_dir_create_and_add(struct class *c
retval = kobject_add(&dir->kobj, parent_kobj, "%s", class->name);
if (retval < 0) {
kobject_put(&dir->kobj);
- return NULL;
+ return ERR_PTR(retval);
}
return &dir->kobj;
}
@@ -1076,6 +1076,10 @@ int device_add(struct device *dev)

parent = get_device(dev->parent);
kobj = get_device_parent(dev, parent);
+ if (IS_ERR(kobj)) {
+ error = PTR_ERR(kobj);
+ goto parent_error;
+ }
if (kobj)
dev->kobj.parent = kobj;

@@ -1174,6 +1178,7 @@ done:
kobject_del(&dev->kobj);
Error:
cleanup_glue_dir(dev, glue_dir);
+parent_error:
put_device(parent);
name_error:
kfree(dev->p);
@@ -1990,6 +1995,11 @@ int device_move(struct device *dev, stru
device_pm_lock();
new_parent = get_device(new_parent);
new_parent_kobj = get_device_parent(dev, new_parent);
+ if (IS_ERR(new_parent_kobj)) {
+ error = PTR_ERR(new_parent_kobj);
+ put_device(new_parent);
+ goto out;
+ }

pr_debug("device: '%s': %s: moving to '%s'\n", dev_name(dev),
__func__, new_parent ? dev_name(new_parent) : "<NULL>");

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