From: Yang Yingliang yangyingliang@huawei.com
[ Upstream commit 1662cea4623f75d8251adf07370bbaa958f0355d ]
Inject fault while loading module, kset_register() may fail. If it fails, the kset.kobj.name allocated by kobject_set_name() which must be called before a call to kset_register() may be leaked, since refcount of kobj was set in kset_init().
To mitigate this, we free the name in kset_register() when an error is encountered, i.e. when kset_register() returns an error.
A kset may be embedded in a larger structure which may be dynamically allocated in callers, it needs to be freed in ktype.release() or error path in callers, in this case, 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 to avoid accessing bad pointer in callers.
With this fix, the callers don't need care about freeing the name and may call kset_put() if kset_register() fails.
Suggested-by: Luben Tuikov luben.tuikov@amd.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com Reviewed-by: luben.tuikov@amd.com Link: https://lore.kernel.org/r/20221025071549.1280528-1-yangyingliang@huawei.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- lib/kobject.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/lib/kobject.c b/lib/kobject.c index a0b2dbfcfa23..3cd19b9ca5ab 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() + * is freed, it can not be used any more. */ int kset_register(struct kset *k) { @@ -844,8 +847,12 @@ int kset_register(struct kset *k)
kset_init(k); err = kobject_add_internal(&k->kobj); - if (err) + if (err) { + kfree_const(k->kobj.name); + /* Set it to NULL to avoid accessing bad pointer in callers. */ + k->kobj.name = NULL; return err; + } kobject_uevent(&k->kobj, KOBJ_ADD); return 0; }