linux-kernel - [PATCH 4.16 37/52] usb: dwc3: gadget: Fix list_del corruption in dwc3_ep

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Date:   Tue,  8 May 2018 10:10:35 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Mayank Rana <mrana@...eaurora.org>,
        Jack Pham <jackp@...eaurora.org>,
        Felipe Balbi <felipe.balbi@...ux.intel.com>
Subject: [PATCH 4.16 37/52] usb: dwc3: gadget: Fix list_del corruption in dwc3_ep_dequeue

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

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

From: Mayank Rana <mrana@...eaurora.org>

commit 96bd39df29c29d348d65311e5954c0b7d3a2a790 upstream.

dwc3_ep_dequeue() waits for completion of End Transfer command using
wait_event_lock_irq(), which will release the dwc3->lock while waiting
and reacquire after completion. This allows a potential race condition
with ep_disable() which also removes all requests from started_list
and pending_list.

The check for NULL r->trb should catch this but currently it exits to
the wrong 'out1' label which calls dwc3_gadget_giveback(). Since its
list entry was already removed, if CONFIG_DEBUG_LIST is enabled a
'list_del corruption' bug is thrown since its next/prev pointers are
already LIST_POISON1/2. If r->trb is NULL it should simply exit to
'out0'.

Fixes: cf3113d893d4 ("usb: dwc3: gadget: properly increment dequeue pointer on ep_dequeue")
Cc: stable@...r.kernel.org # v4.12+
Signed-off-by: Mayank Rana <mrana@...eaurora.org>
Signed-off-by: Jack Pham <jackp@...eaurora.org>
Signed-off-by: Felipe Balbi <felipe.balbi@...ux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/usb/dwc3/gadget.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1424,7 +1424,7 @@ static int dwc3_gadget_ep_dequeue(struct
 					dwc->lock);

 			if (!r->trb)
-				goto out1;
+				goto out0;

 			if (r->num_pending_sgs) {
 				struct dwc3_trb *trb;