Patch "usb: gadget: don't dereference g until after it has been null checked" has been added to the 4.9-stable tree

Patch "usb: gadget: don't dereference g until after it has been null checked" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    usb: gadget: don't dereference g until after it has been null checked

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     usb-gadget-don-t-dereference-g-until-after-it-has-been-null-checked.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Thu Feb  1 14:00:34 CET 2018
From: Colin Ian King <colin.king@canonical.com>
Date: Tue, 14 Nov 2017 16:18:28 +0000
Subject: usb: gadget: don't dereference g until after it has been null checked

From: Colin Ian King <colin.king@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.king@canonical.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@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;
 		}


Patches currently in stable-queue which might be from colin.king@canonical.com are

queue-4.9/usb-gadget-don-t-dereference-g-until-after-it-has-been-null-checked.patch