[PATCH v3 1/2] usb: dwc3: gadget: Stop processing more requests on IMI

[Thinh Nguyen <Thinh.Nguyen@synopsys.com>]

When servicing a transfer completion event, the dwc3 driver will reclaim
TRBs of started requests up to the request associated with the interrupt
event. Currently we don't check for interrupt due to missed isoc, and
the driver may attempt to reclaim TRBs beyond the associated event. This
causes invalid memory access when the hardware still owns the TRB. If
there's a missed isoc TRB with IMI (interrupt on missed isoc), make sure
to stop servicing further.

Note that only the last TRB of chained TRBs has its status updated with
missed isoc.

Fixes: 72246da40f37 ("usb: Introduce DesignWare USB3 DRD Driver")
Cc: stable@vger.kernel.org
Reported-by: Jeff Vanhoof <jdv1029@gmail.com>
Reported-by: Dan Vacura <w36195@motorola.com>
Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
---
 Changes in v3:
 - None
 Changes in v2:
 - No need to check for CHN=0 since only the last TRB has its status
 updated to missed isoc


 drivers/usb/dwc3/gadget.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index dd8ecbe61bec..230b3c660054 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -3248,6 +3248,10 @@ static int dwc3_gadget_ep_reclaim_completed_trb(struct dwc3_ep *dep,
 	if (event->status & DEPEVT_STATUS_SHORT && !chain)
 		return 1;
 
+	if ((trb->ctrl & DWC3_TRB_CTRL_ISP_IMI) &&
+	    DWC3_TRB_SIZE_TRBSTS(trb->size) == DWC3_TRBSTS_MISSED_ISOC)
+		return 1;
+
 	if ((trb->ctrl & DWC3_TRB_CTRL_IOC) ||
 	    (trb->ctrl & DWC3_TRB_CTRL_LST))
 		return 1;
-- 
2.28.0