Re: [PATCH] drivers/media/rc: Ensure usb_submit_urb() is not called if write is in progress

[Greg KH <gregkh@linuxfoundation.org>]

On Sun, Aug 14, 2022 at 07:55:42PM +0530, Gautam Menghani wrote:
> The warning "URB submitted while active" is reported if the function
> send_packet() in imon.c is called if a write is already is in progress.
> Add a check to return -EBUSY in case a write is already is in progress.
> Also, mark tx.busy as false after transmission is completed.
> 
> Fixes: 21677cfc562a ("V4L/DVB: ir-core: add imon driver")
> Cc: hdanton@sina.com
> Suggested-by: hdanton@sina.com
> Link: https://syzkaller.appspot.com/bug?id=e378e6a51fbe6c5cc43e34f131cc9a315ef0337e
> Reported-by: syzbot+0c3cb6dc05fbbdc3ad66@syzkaller.appspotmail.com
> Signed-off-by: Gautam Menghani <gautammenghani201@gmail.com>
> ---
>  drivers/media/rc/imon.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/media/rc/imon.c b/drivers/media/rc/imon.c
> index 735b925da998..a5b997c2c7e2 100644
> --- a/drivers/media/rc/imon.c
> +++ b/drivers/media/rc/imon.c
> @@ -598,6 +598,8 @@ static int send_packet(struct imon_context *ictx)
>  	int retval = 0;
>  	struct usb_ctrlrequest *control_req = NULL;
>  
> +	if (ictx->tx.busy)
> +		return -EBUSY;

What happens if we go busy right after this check?  Where is the locking
here to protect this?

thanks,

greg k-h