On Wed, May 04, 2022 at 03:28:02PM +0800, Albert Wang wrote:
> There are still race conditions to hit the null pointer deference
> with my previous commit. So I re-write the code to dereference the
> pointer right after checking it is not null.
What race conditions?
And just moving it is not going to solve a race condition, you need a
lock.
>
> Fixes: 26288448120b ("usb: dwc3: gadget: Fix null pointer exception")
>
> Signed-off-by: Albert Wang <albertccwang@xxxxxxxxxx>
> ---
> drivers/usb/dwc3/gadget.c | 7 +++----
> 1 file changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 19477f4bbf54..f2792968afd9 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -3366,15 +3366,14 @@ static bool dwc3_gadget_endpoint_trbs_complete(struct dwc3_ep *dep,
> struct dwc3 *dwc = dep->dwc;
> bool no_started_trb = true;
>
> - if (!dep->endpoint.desc)
> - return no_started_trb;
> -
> dwc3_gadget_ep_cleanup_completed_requests(dep, event, status);
>
> if (dep->flags & DWC3_EP_END_TRANSFER_PENDING)
> goto out;
>
> - if (usb_endpoint_xfer_isoc(dep->endpoint.desc) &&
> + if (!dep->endpoint.desc)
> + return no_started_trb;
> + else if (usb_endpoint_xfer_isoc(dep->endpoint.desc) &&
There is no locking here, so why would this change do anything but
reduce the window?
thanks,
greg k-h
