[PATCH v2] usb: gadget: forbid queuing request to a disabled ep

From: changbin . du
Date: Sun Dec 13 2015 - 22:57:25 EST

From: "Du, Changbin" <changbin.du@xxxxxxxxx>

Queue a request to disabled ep doesn't make sense, and induce caller
make mistakes.

Here is a example for the android mtp gadget function driver. A mem
corruption can happen on below senario.
1) On disconnect, mtp driver disable its EPs,
2) During send_file_work and receive_file_work, mtp queues a request
to ep. (The mtp driver need improve its synchronization logic!)
3) mtp_function_unbind is invoked and all mtp requests are freed.
4) when udc process the request queued on step 2, will cause kernel
NULL pointer dereference exception.

Signed-off-by: Du, Changbin <changbin.du@xxxxxxxxx>
change from v1: add WARN_ON_ONCE message.

include/linux/usb/gadget.h | 3 +++
1 file changed, 3 insertions(+)

diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
index 3d583a1..b566a4b 100644
--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -402,6 +402,9 @@ static inline void usb_ep_free_request(struct usb_ep *ep,
static inline int usb_ep_queue(struct usb_ep *ep,
struct usb_request *req, gfp_t gfp_flags)
+ if (WARN_ON_ONCE(!ep->enabled))
+ return -ESHUTDOWN;
return ep->ops->queue(ep, req, gfp_flags);


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/