[PATCH 4.19 24/98] usb: musb: Get the musb_qh poniter after musb_giveback

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

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

From: Xingxing Luo <xingxing.luo@xxxxxxxxxx>

commit 33d7e37232155aadebe4145dcc592f00dabd7a2b upstream.

When multiple threads are performing USB transmission, musb->lock will be
unlocked when musb_giveback is executed. At this time, qh may be released
in the dequeue process in other threads, resulting in a wild pointer, so
it needs to be here get qh again, and judge whether qh is NULL, and when
dequeue, you need to set qh to NULL.

Fixes: dbac5d07d13e ("usb: musb: host: don't start next rx urb if current one failed")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Xingxing Luo <xingxing.luo@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230919033055.14085-1-xingxing.luo@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/usb/musb/musb_host.c |    9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

--- a/drivers/usb/musb/musb_host.c
+++ b/drivers/usb/musb/musb_host.c
@@ -339,10 +339,16 @@ static void musb_advance_schedule(struct
 	musb_giveback(musb, urb, status);
 	qh->is_ready = ready;
 
+	/*
+	 * musb->lock had been unlocked in musb_giveback, so qh may
+	 * be freed, need to get it again
+	 */
+	qh = musb_ep_get_qh(hw_ep, is_in);
+
 	/* reclaim resources (and bandwidth) ASAP; deschedule it, and
 	 * invalidate qh as soon as list_empty(&hep->urb_list)
 	 */
-	if (list_empty(&qh->hep->urb_list)) {
+	if (qh && list_empty(&qh->hep->urb_list)) {
 		struct list_head	*head;
 		struct dma_controller	*dma = musb->dma_controller;
 
@@ -2424,6 +2430,7 @@ static int musb_urb_dequeue(struct usb_h
 		 * and its URB list has emptied, recycle this qh.
 		 */
 		if (ready && list_empty(&qh->hep->urb_list)) {
+			musb_ep_set_qh(qh->hw_ep, is_in, NULL);
 			qh->hep->hcpriv = NULL;
 			list_del(&qh->ring);
 			kfree(qh);





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