Re: [PATCH] usb: dwc3: gadget: Prevent EP queuing while stopping transfers

Jack Pham
2021-03-10T18:10:37Z

Hi Wesley,

On Wed, Mar 10, 2021 at 03:02:10AM -0800, Wesley Cheng wrote:
> In the situations where the DWC3 gadget stops active transfers, once
> calling the dwc3_gadget_giveback(), there is a chance where a function
> driver can queue a new USB request in between the time where the dwc3
> lock has been released and re-aquired. This occurs after we've already
> issued an ENDXFER command. When the stop active transfers continues
> to remove USB requests from all dep lists, the newly added request will
> also be removed, while controller still has an active TRB for it.
> This can lead to the controller accessing an unmapped memory address.
>
> Fix this by ensuring parameters to prevent EP queuing are set before
> calling the stop active transfers API.

Is it correct to say this Fixes: ae7e86108b12 ("usb: dwc3: Stop active
transfers before halting the controller") ?

Jack

> Signed-off-by: Wesley Cheng <wcheng@codeaurora.org>
> ---
> drivers/usb/dwc3/gadget.c | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 4780983..4d98fbf 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -783,8 +783,6 @@ static int __dwc3_gadget_ep_disable(struct dwc3_ep *dep)
>
> trace_dwc3_gadget_ep_disable(dep);
>
> - dwc3_remove_requests(dwc, dep);
> -
> /* make sure HW endpoint isn't stalled */
> if (dep->flags & DWC3_EP_STALL)
> __dwc3_gadget_ep_set_halt(dep, 0, false);
> @@ -803,6 +801,8 @@ static int __dwc3_gadget_ep_disable(struct dwc3_ep *dep)
> dep->endpoint.desc = NULL;
> }
>
> + dwc3_remove_requests(dwc, dep);
> +
> return 0;
> }
>
> @@ -1617,7 +1617,7 @@ static int __dwc3_gadget_ep_queue(struct dwc3_ep *dep, struct dwc3_request *req)
> {
> struct dwc3 *dwc = dep->dwc;
>
> - if (!dep->endpoint.desc || !dwc->pullups_connected) {
> + if (!dep->endpoint.desc || !dwc->pullups_connected || !dwc->connected) {
> dev_err(dwc->dev, "%s: can't queue to disabled endpoint\n",
> dep->name);
> return -ESHUTDOWN;
> @@ -2247,6 +2247,7 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
> if (!is_on) {
> u32 count;
>
> + dwc->connected = false;
> /*
> * In the Synopsis DesignWare Cores USB3 Databook Rev. 3.30a
> * Section 4.1.8 Table 4-7, it states that for a device-initiated
> @@ -3329,8 +3330,6 @@ static void dwc3_gadget_reset_interrupt(struct dwc3 *dwc)
> {
> u32 reg;
>
> - dwc->connected = true;
> -
> /*
> * WORKAROUND: DWC3 revisions <1.88a have an issue which
> * would cause a missing Disconnect Event if there's a
> @@ -3370,6 +3369,7 @@ static void dwc3_gadget_reset_interrupt(struct dwc3 *dwc)
> * transfers."
> */
> dwc3_stop_active_transfers(dwc);
> + dwc->connected = true;
>
> reg = dwc3_readl(dwc->regs, DWC3_DCTL);
> reg &= ~DWC3_DCTL_TSTCTRL_MASK;
--
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