linux-kernel - [PATCH] USB: core: Fix potental Null Pointer dereference

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Date:   Wed,  9 Oct 2019 18:02:02 -0700
From:   Yizhuo <yzhai003@....edu>
To:     unlisted-recipients:; (no To-header on input)
Cc:     Yizhuo <yzhai003@....edu>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Alan Stern <stern@...land.harvard.edu>,
        Kai-Heng Feng <kai.heng.feng@...onical.com>,
        Mathias Nyman <mathias.nyman@...ux.intel.com>,
        Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        Douglas Anderson <dianders@...omium.org>,
        Nicolas Saenz Julienne <nsaenzjulienne@...e.de>,
        Jan-Marek Glogowski <glogow@...home.de>,
        Mathieu Malaterre <malat@...ian.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] USB: core: Fix potental Null Pointer dereference

Inside function usb_device_is_owned(), usb_hub_to_struct_hub()
could return NULL but there's no check before its dereference,
which is potentially unsafe.

Signed-off-by: Yizhuo <yzhai003@....edu>
---
 drivers/usb/core/hub.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 236313f41f4a..8d628c8e0c1b 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -1977,7 +1977,7 @@ bool usb_device_is_owned(struct usb_device *udev)
 	if (udev->state == USB_STATE_NOTATTACHED || !udev->parent)
 		return false;
 	hub = usb_hub_to_struct_hub(udev->parent);
-	return !!hub->ports[udev->portnum - 1]->port_owner;
+	return hub && !!hub->ports[udev->portnum - 1]->port_owner;
 }
 
 static void recursively_mark_NOTATTACHED(struct usb_device *udev)
-- 
2.17.1