usb: dwc2: host: fix use of qtd after free in desc dma mode

When completing non isoc xfer, dwc2_complete_non_isoc_xfer_ddma()
is relying on qtd->n_desc to process the corresponding number of
descriptors.

During the processing of these descriptors, qtd could be unlinked
and freed if xfer is done and urb is no more in progress.

In this case, dwc2_complete_non_isoc_xfer_ddma() will read again
qtd->n_desc whereas qtd has been freed. This will lead to unpredictable
results since qtd->n_desc is no more valid value.

To avoid this error, return a result != 0 in dwc2_process_non_isoc_desc(),
so that dwc2_complete_non_isoc_xfer_ddma() stops desc processing.

This has been seen with Slub debug enabled.

Acked-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Gregory Herrero <gregory.herrero@intel.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

diff --git a/drivers/usb/dwc2/hcd_ddma.c b/drivers/usb/dwc2/hcd_ddma.c
index 5f7265637334406dd4cfc11c3558618c9321dcde..4801e693353a4f9220ab0e391449ea69b22bf33e 100644 (file)
--- a/drivers/usb/dwc2/hcd_ddma.c
+++ b/drivers/usb/dwc2/hcd_ddma.c
@@ -1033,7 +1033,10 @@ static int dwc2_process_non_isoc_desc(struct dwc2_hsotg *hsotg,
        failed = dwc2_update_non_isoc_urb_state_ddma(hsotg, chan, qtd, dma_desc,
                                                     halt_status, n_bytes,
                                                     xfer_done);
-       if (failed || (*xfer_done && urb->status != -EINPROGRESS)) {
+       if (*xfer_done && urb->status != -EINPROGRESS)
+               failed = 1;
+
+       if (failed) {
                dwc2_host_complete(hsotg, qtd, urb->status);
                dwc2_hcd_qtd_unlink_and_free(hsotg, qtd, qh);
                dev_vdbg(hsotg->dev, "failed=%1x xfer_done=%1x status=%08x\n",