usb: acpi: Prevent null pointer dereference in usb_acpi_add_usb4_devlink()

As demonstrated by the fix for update_port_device_state,
commit 12783c0b9e2c ("usb: core: Prevent null pointer dereference in update_port_device_state"),
usb_hub_to_struct_hub() can return NULL in certain scenarios,
such as during hub driver unbind or teardown race conditions,
even if the underlying usb_device structure exists.

Plus, all other places that call usb_hub_to_struct_hub() in the same file
do check for NULL return values.

If usb_hub_to_struct_hub() returns NULL, the subsequent access to
hub->ports[udev->portnum - 1] will cause a null pointer dereference.

Signed-off-by: Chenyuan Yang <chenyuan0y@gmail.com>
Fixes: f1bfb4a6fed6 ("usb: acpi: add device link between tunneled USB3 device and USB4 Host Interface")
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/20250417195032.1811338-1-chenyuan0y@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/core/usb-acpi.c b/drivers/usb/core/usb-acpi.c
index 935c0efea0b640b448a5161b3d0555cf38530eed..ea1ce8beb0cbb27adea84f640c1625a75f5861be 100644 (file)
--- a/drivers/usb/core/usb-acpi.c
+++ b/drivers/usb/core/usb-acpi.c
@@ -165,6 +165,8 @@ static int usb_acpi_add_usb4_devlink(struct usb_device *udev)
                return 0;
 
        hub = usb_hub_to_struct_hub(udev->parent);
+       if (!hub)
+               return 0;
        port_dev = hub->ports[udev->portnum - 1];
 
        struct fwnode_handle *nhi_fwnode __free(fwnode_handle) =