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

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Message-ID: <YvkKdIL8UVhKrI0Q@kroah.com>
Date:   Sun, 14 Aug 2022 16:45:08 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Gautam Menghani <gautammenghani201@...il.com>
Cc:     sean@...s.org, mchehab@...nel.org, hdanton@...a.com,
        linux-kernel@...r.kernel.org,
        syzbot+0c3cb6dc05fbbdc3ad66@...kaller.appspotmail.com,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        linux-media@...r.kernel.org
Subject: Re: [PATCH] drivers/media/rc: Ensure usb_submit_urb() is not called
 if write is in progress

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@...a.com
> Suggested-by: hdanton@...a.com
> Link: https://syzkaller.appspot.com/bug?id=e378e6a51fbe6c5cc43e34f131cc9a315ef0337e
> Reported-by: syzbot+0c3cb6dc05fbbdc3ad66@...kaller.appspotmail.com
> Signed-off-by: Gautam Menghani <gautammenghani201@...il.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