[PATCH 4.9 68/86] usb: gadget: dont dereference g until after it has been null checked

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Colin Ian King <colin.k...@canonical.com>


[ Upstream commit b2fc059fa549fe6881d4c1f8d698b0f50bcd16ec ]

Avoid dereferencing pointer g until after g has been sanity null checked;
move the assignment of cdev much later when it is required into a more
local scope.

Detected by CoverityScan, CID#1222135 ("Dereference before null check")

Fixes: b785ea7ce662 ("usb: gadget: composite: fix ep->maxburst initialization")
Signed-off-by: Colin Ian King <colin.k...@canonical.com>
Signed-off-by: Felipe Balbi <felipe.ba...@linux.intel.com>
Signed-off-by: Sasha Levin <alexander.le...@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 drivers/usb/gadget/composite.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -150,7 +150,6 @@ int config_ep_by_speed(struct usb_gadget
                        struct usb_function *f,
                        struct usb_ep *_ep)
 {
-       struct usb_composite_dev        *cdev = get_gadget_data(g);
        struct usb_endpoint_descriptor *chosen_desc = NULL;
        struct usb_descriptor_header **speed_desc = NULL;
 
@@ -229,8 +228,12 @@ ep_found:
                        _ep->maxburst = comp_desc->bMaxBurst + 1;
                        break;
                default:
-                       if (comp_desc->bMaxBurst != 0)
+                       if (comp_desc->bMaxBurst != 0) {
+                               struct usb_composite_dev *cdev;
+
+                               cdev = get_gadget_data(g);
                                ERROR(cdev, "ep0 bMaxBurst must be 0\n");
+                       }
                        _ep->maxburst = 1;
                        break;
                }