usb: gadget: u_audio: fix race condition on endpoint stop

[ Upstream commit 068fdad20454f815e61e6f6eb9f051a8b3120e88 ]

If the endpoint completion callback is call right after the ep_enabled flag
is cleared and before usb_ep_dequeue() is call, we could do a double free
on the request and the associated buffer.

Fix this by clearing ep_enabled after all the endpoint requests have been
dequeued.

Fixes: 7de8681be2cd ("usb: gadget: u_audio: Free requests only after callback")
Cc: stable <stable@vger.kernel.org>
Reported-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Link: https://lore.kernel.org/r/20210827092927.366482-1-jbrunet@baylibre.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/usb/gadget/function/u_audio.c b/drivers/usb/gadget/function/u_audio.c
index 5fbceee897a3f2bfa0a17fb05bf7a1b90a5d0a39..3b613ca06ae55740d820a1feb84caf23b51a645f 100644 (file)
--- a/drivers/usb/gadget/function/u_audio.c
+++ b/drivers/usb/gadget/function/u_audio.c
@@ -312,8 +312,6 @@ static inline void free_ep(struct uac_rtd_params *prm, struct usb_ep *ep)
        if (!prm->ep_enabled)
                return;
 
-       prm->ep_enabled = false;
-
        audio_dev = uac->audio_dev;
        params = &audio_dev->params;
 
@@ -331,11 +329,12 @@ static inline void free_ep(struct uac_rtd_params *prm, struct usb_ep *ep)
                }
        }
 
+       prm->ep_enabled = false;
+
        if (usb_ep_disable(ep))
                dev_err(uac->card->dev, "%s:%d Error!\n", __func__, __LINE__);
 }
 
-
 int u_audio_start_capture(struct g_audio *audio_dev)
 {
        struct snd_uac_chip *uac = audio_dev->uac;