usb: gadget: composite: Fix NULL pointer dereference

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@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

1 files changed, 7 insertions, 4 deletions

diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index 4e3447bbd097..58b4657fc721 100644
--- 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)