On Mon, Oct 24, 2022 at 08:19:10PM +0800, Yang Yingliang wrote:
> Inject fault while loading module, kset_register() may fail.
> If it fails, the name allocated by kobject_set_name() which
> is called before kset_register() is leaked, because refcount
> of kobject is hold in kset_init().
>
> As a kset may be embedded in a larger structure which needs
> be freed in release() function or error path in callers, we
> can not call kset_put() in kset_register(), or it will cause
> double free, so just call kfree_const() to free the name and
> set it to NULL.
>
> With this fix, the callers don't need to care about the name
> freeing and call an extra kset_put() if kset_register() fails.
>
> Suggested-by: Luben Tuikov <luben.tuikov@xxxxxxx>
> Signed-off-by: Yang Yingliang <yangyingliang@xxxxxxxxxx>
> ---
> v1 -> v2:
> Free name inside of kset_register() instead of calling kset_put()
> in drivers.
> ---
> lib/kobject.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/lib/kobject.c b/lib/kobject.c
> index a0b2dbfcfa23..3409a89c81e5 100644
> --- a/lib/kobject.c
> +++ b/lib/kobject.c
> @@ -834,6 +834,9 @@ EXPORT_SYMBOL_GPL(kobj_sysfs_ops);
> /**
> * kset_register() - Initialize and add a kset.
> * @k: kset.
> + *
> + * NOTE: On error, the kset.kobj.name allocated by() kobj_set_name()
> + * which is called before kset_register() in caller need be freed.
This comment doesn't make any sense anymore. No caller needs to worry
about this, right?
> */
> int kset_register(struct kset *k)
> {
> @@ -844,8 +847,11 @@ int kset_register(struct kset *k)
>
> kset_init(k);
> err = kobject_add_internal(&k->kobj);
> - if (err)
> + if (err) {
> + kfree_const(k->kobj.name);
> + k->kobj.name = NULL;
Why are you setting the name here to NULL?
thanks,
greg k-h
