4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxxxxxx> Reported-by: syzbot <syzbot+df47f81c226b31d89fb1@xxxxxxxxxxxxxxxxxxxxxxxxx> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Cc: stable <stable@xxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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>");
