linux-kernel - [PATCH 4.1 102/267] usb: gadget: composite: Fix NULL pointer dereference

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Date:	Fri, 31 Jul 2015 12:39:13 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Kishon Vijay Abraham I <kishon@...com>,
	Felipe Balbi <balbi@...com>
Subject: [PATCH 4.1 102/267] usb: gadget: composite: Fix NULL pointer dereference

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

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

From: Kishon Vijay Abraham I <kishon@...com>

commit b4c21f0bdd2c0cd5d5be1bb56f0a28dae5041eed upstream.

commit f563d230903210acc ("usb: gadget: composite: add req_match method
to usb_function") accesses cdev->config even before set config
is invoked causing a NULL pointer dereferencing error while running
Lecroy Mass Storage Compliance test.

Fix it here by accessing cdev->config only if it is non NULL.

Fixes: commit f563d230903210acc ("usb: gadget: composite: add req_match
method to usb_function").

Signed-off-by: Kishon Vijay Abraham I <kishon@...com>
Signed-off-by: Felipe Balbi <balbi@...com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/usb/gadget/composite.c |   11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -1758,10 +1758,13 @@ unknown:
 		 * take such requests too, if that's ever needed:  to work
 		 * in config 0, etc.
 		 */
-		list_for_each_entry(f, &cdev->config->functions, list)
-			if (f->req_match && f->req_match(f, ctrl))
-				goto try_fun_setup;
-		f = NULL;
+		if (cdev->config) {
+			list_for_each_entry(f, &cdev->config->functions, list)
+				if (f->req_match && f->req_match(f, ctrl))
+					goto try_fun_setup;
+			f = NULL;
+		}
+
 		switch (ctrl->bRequestType & USB_RECIP_MASK) {
 		case USB_RECIP_INTERFACE:
 			if (!cdev->config || intf >= MAX_CONFIG_INTERFACES)


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