[PATCH] debug: Fix a NULL vs IS_ERR() bug in __debug_object_init()

[Haotian Zhang <vulab@iscas.ac.cn>]

The lookup_object_or_alloc() returns error pointers on failure, but the
code only checks for NULL. This leads to dereferencing an invalid error
pointer and causes a kernel crash.

Use IS_ERR_OR_NULL() instead of a NULL check to properly handle both
error pointers and NULL returns.

Fixes: 63a759694eed ("debugobject: Prevent init race with static objects")
Signed-off-by: Haotian Zhang <vulab@iscas.ac.cn>
---
 lib/debugobjects.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/debugobjects.c b/lib/debugobjects.c
index 7f50c4480a4e..9587ef619054 100644
--- a/lib/debugobjects.c
+++ b/lib/debugobjects.c
@@ -741,9 +741,10 @@ __debug_object_init(void *addr, const struct debug_obj_descr *descr, int onstack
 	raw_spin_lock_irqsave(&db->lock, flags);
 
 	obj = lookup_object_or_alloc(addr, db, descr, onstack, false);
-	if (unlikely(!obj)) {
+	if (IS_ERR_OR_NULL(obj)) {
 		raw_spin_unlock_irqrestore(&db->lock, flags);
-		debug_objects_oom();
+		if (!obj)
+			debug_objects_oom();
 		return;
 	}
 
-- 
2.50.1.windows.1