[PATCH AUTOSEL 6.4 22/25] kobject: Add sanity check for kset->kobj.ktype in kset_register()

Sasha Levin
2023-09-09T00:42:08Z

From: Zhen Lei <thunder.leizhen@huawei.com>

[ Upstream commit 4d0fe8c52bb3029d83e323c961221156ab98680b ]

When I register a kset in the following way:
static struct kset my_kset;
kobject_set_name(&my_kset.kobj, "my_kset");
ret = kset_register(&my_kset);

A null pointer dereference exception is occurred:
[ 4453.568337] Unable to handle kernel NULL pointer dereference at \
virtual address 0000000000000028
... ...
[ 4453.810361] Call trace:
[ 4453.813062] kobject_get_ownership+0xc/0x34
[ 4453.817493] kobject_add_internal+0x98/0x274
[ 4453.822005] kset_register+0x5c/0xb4
[ 4453.825820] my_kobj_init+0x44/0x1000 [my_kset]
... ...

Because I didn't initialize my_kset.kobj.ktype.

According to the description in Documentation/core-api/kobject.rst:
- A ktype is the type of object that embeds a kobject. Every structure
that embeds a kobject needs a corresponding ktype.

So add sanity check to make sure kset->kobj.ktype is not NULL.

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/r/20230805084114.1298-2-thunder.leizhen@huaweicloud.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
lib/kobject.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/lib/kobject.c b/lib/kobject.c
index f79a434e12316..7feefcabfc4ab 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -855,6 +855,11 @@ int kset_register(struct kset *k)
if (!k)
return -EINVAL;

+ if (!k->kobj.ktype) {
+ pr_err("must have a ktype to be initialized properly!\n");
+ return -EINVAL;
+ }
+
kset_init(k);
err = kobject_add_internal(&k->kobj);
if (err) {
--
2.40.1