[PATCH] usb: gadget: composite: don't queue OS desc req if length is invalid

[William Wu]

In OS descriptors handling, if ctrl->bRequestType is
USB_RECIP_DEVICE and w_index != 0x4 or (w_value >> 8)
is true, it will not assign a valid value to req->length,
but use the default value(-EOPNOTSUPP), and queue an
OS desc request with the invalid req->length. It always
happens on the platforms which use os_desc (for example:
rk3366, rk3399), and cause kernel panic as follows
(use dwc3 driver):

Unable to handle kernel paging request at virtual address ffffffc0f7e00000
Internal error: Oops: 96000146 [#1] PREEMPT SMP
PC is at __dma_clean_range+0x18/0x30
LR is at __swiotlb_map_page+0x50/0x64
Call trace:
[<ffffffc0000930f8>] __dma_clean_range+0x18/0x30
[<ffffffc00062214c>] usb_gadget_map_request+0x134/0x1b0
[<ffffffc0005c289c>] __dwc3_ep0_do_control_data+0x110/0x14c
[<ffffffc0005c2d38>] __dwc3_gadget_ep0_queue+0x198/0x1b8
[<ffffffc0005c2e18>] dwc3_gadget_ep0_queue+0xc0/0xe8
[<ffffffc00061cfec>] composite_ep0_queue.constprop.14+0x34/0x98
[<ffffffc00061dfb0>] composite_setup+0xf60/0x100c
[<ffffffc0006204dc>] android_setup+0xd8/0x138
[<ffffffc0005c29a4>] dwc3_ep0_delegate_req+0x34/0x50
[<ffffffc0005c3534>] dwc3_ep0_interrupt+0x5dc/0xb58
[<ffffffc0005c0c3c>] dwc3_thread_interrupt+0x15c/0xa24

With this patch, the gadget driver will not queue
a request and return immediately if req->length is
invalid. And the usb controller driver can handle
the unsupport request correctly.

Signed-off-by: William Wu <william.wu@xxxxxxxxxxxxxx>
---
 drivers/usb/gadget/composite.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index d67de0d..eb64848 100644
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -1868,14 +1868,19 @@ unknown:
 				}
 				break;
 			}
-			req->length = value;
-			req->context = cdev;
-			req->zero = value < w_length;
-			value = composite_ep0_queue(cdev, req, GFP_ATOMIC);
-			if (value < 0) {
-				DBG(cdev, "ep_queue --> %d\n", value);
-				req->status = 0;
-				composite_setup_complete(gadget->ep0, req);
+
+			if (value >= 0) {
+				req->length = value;
+				req->context = cdev;
+				req->zero = value < w_length;
+				value = composite_ep0_queue(cdev, req,
+							    GFP_ATOMIC);
+				if (value < 0) {
+					DBG(cdev, "ep_queue --> %d\n", value);
+					req->status = 0;
+					composite_setup_complete(gadget->ep0,
+								 req);
+				}
 			}
 			return value;
 		}
-- 
1.9.1