linux-kernel - [PATCH V3] usb: musb: Get the musb_qh poniter after musb

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Message-ID: <20230919033055.14085-1-xingxing.luo@unisoc.com>
Date:   Tue, 19 Sep 2023 11:30:55 +0800
From:   Xingxing Luo <xingxing.luo@...soc.com>
To:     <b-liu@...com>, <gregkh@...uxfoundation.org>, <s.shtylyov@....ru>
CC:     <linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <xingxing0070.luo@...il.com>, <Zhiyong.Liu@...soc.com>,
        <Cixi.Geng1@...soc.com>, <Orson.Zhai@...soc.com>,
        <zhang.lyra@...il.com>
Subject: [PATCH V3] usb: musb: Get the musb_qh poniter after musb_giveback

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@...r.kernel.org
Signed-off-by: Xingxing Luo <xingxing.luo@...soc.com>
---
v2 -> v3: Add Cc: stable
v1 -> v2: - Modified the comments section.
          - Modified "if (qh != NULL && ..." to "if (qh && ...".

 drivers/usb/musb/musb_host.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c
index a02c29216955..bc4507781167 100644
--- a/drivers/usb/musb/musb_host.c
+++ b/drivers/usb/musb/musb_host.c
@@ -321,10 +321,16 @@ static void musb_advance_schedule(struct musb *musb, struct urb *urb,
 	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;
 
@@ -2398,6 +2404,7 @@ static int musb_urb_dequeue(struct usb_hcd *hcd, struct urb *urb, int status)
 		 * 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);
-- 
2.17.1