From 96bd39df29c29d348d65311e5954c0b7d3a2a790 Mon Sep 17 00:00:00 2001
From: Mayank Rana <mrana@codeaurora.org>
Date: Fri, 23 Mar 2018 10:05:33 -0700
Subject: [PATCH] usb: dwc3: gadget: Fix list_del corruption in dwc3_ep_dequeue
Git-commit: 96bd39df29c29d348d65311e5954c0b7d3a2a790
No-fix: 05645366f3893c160bd39ca49f3fe2f2f026f58b
Patch-mainline: v4.17-rc4
References: bsc#1051510

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@vger.kernel.org # v4.12+
Signed-off-by: Mayank Rana <mrana@codeaurora.org>
Signed-off-by: Jack Pham <jackp@codeaurora.org>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

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

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 206ecc7428da..0dedf8a799f4 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1424,7 +1424,7 @@ static int dwc3_gadget_ep_dequeue(struct usb_ep *ep,
 					dwc->lock);
 
 			if (!r->trb)
-				goto out1;
+				goto out0;
 
 			if (r->num_pending_sgs) {
 				struct dwc3_trb *trb;
-- 
2.18.0