[PATCH] IB/mlx4: Fix refcount leak in add_port() error path

[Guangshuo Li]

After kobject_init_and_add(), the lifetime of the embedded struct
kobject is expected to be managed through the kobject core reference
counting.

In add_port(), if kobject_init_and_add() fails, the error path frees p
directly instead of releasing the kobject reference with kobject_put().
This may leave the reference count of the embedded struct kobject
unbalanced, resulting in a refcount leak and potentially leading to a
use-after-free.

Fix this by using kobject_put(&p->kobj) in the kobject_init_and_add()
failure path.

Fixes: c1e7e466120b ("IB/mlx4: Add iov directory in sysfs under the ib device")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Guangshuo Li <lgs201920130244@xxxxxxxxx>
---
 drivers/infiniband/hw/mlx4/sysfs.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/hw/mlx4/sysfs.c b/drivers/infiniband/hw/mlx4/sysfs.c
index 88f534cf690e..15b36b9e4bd6 100644
--- a/drivers/infiniband/hw/mlx4/sysfs.c
+++ b/drivers/infiniband/hw/mlx4/sysfs.c
@@ -642,7 +642,7 @@ static int add_port(struct mlx4_ib_dev *dev, int port_num, int slave)
 				   kobject_get(dev->dev_ports_parent[slave]),
 				   "%d", port_num);
 	if (ret)
-		goto err_alloc;
+		goto err_kobj;
 
 	p->pkey_group.name  = "pkey_idx";
 	p->pkey_group.attrs =
@@ -689,6 +689,11 @@ static int add_port(struct mlx4_ib_dev *dev, int port_num, int slave)
 	kobject_put(dev->dev_ports_parent[slave]);
 	kfree(p);
 	return ret;
+
+err_kobj:
+	kobject_put(&p->kobj);
+	return ret;
+
 }
 
 static int register_one_pkey_tree(struct mlx4_ib_dev *dev, int slave)
-- 
2.43.0