[PATCH][next] kobject: fix dereference before null check on kobj

From: Colin King
Date: Wed May 01 2019 - 08:43:34 EST

From: Colin Ian King <colin.king@xxxxxxxxxxxxx>

The kobj pointer is being null-checked so potentially it could be null,
however, the ktype declaration before the null check is dereferencing kobj
hence we have a potential null pointer deference. Fix this by moving the
assignment of ktype after kobj has been null checked.

Addresses-Coverity: ("Dereference before null check")
Fixes: aa30f47cf666 ("kobject: Add support for default attribute groups to kobj_type")
Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
lib/kobject.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/kobject.c b/lib/kobject.c
index a30ee0467942..095bcb55c2ba 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -603,12 +603,13 @@ EXPORT_SYMBOL_GPL(kobject_move);
void kobject_del(struct kobject *kobj)
struct kernfs_node *sd;
- const struct kobj_type *ktype = get_ktype(kobj);
+ const struct kobj_type *ktype;

if (!kobj)

sd = kobj->sd;
+ ktype = get_ktype(kobj);

if (ktype)
sysfs_remove_groups(kobj, ktype->default_groups);