From: Zhen Lei <[email protected]>
Currently, there are four API paths for adding or registering kobjects:
1. Call kobject_init() first then kobject_add()
2. kobject_init_and_add()
3. kset_register()
4. kset_create_and_add()
Except for kset_register(), the other three paths ensure that kobj.ktype cannot be NULL.
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.
Add sanity check for kset->kobj.ktype in kset_register(), make sure that it cannot be NULL,
then all added or registered kobj/kset.obj, its ktype is not NULL. We can safely remove all
statements that check whether kobj.ktype is NULL. They're redundant.
Zhen Lei (2):
kobject: Add sanity check for kset->kobj.ktype in kset_register()
kobject: Remove redundant checks for whether ktype is NULL
lib/kobject.c | 29 +++++++++++++++--------------
1 file changed, 15 insertions(+), 14 deletions(-)
--
2.34.1
From: Zhen Lei <[email protected]>
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 <[email protected]>
---
lib/kobject.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/lib/kobject.c b/lib/kobject.c
index 14e845209226ab8..72fa20f405f1520 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -861,6 +861,11 @@ 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) {
--
2.34.1