linux-kernel - Re: [PATCH] serial: rp2: disable interrupt in rp2

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Date:   Fri, 21 May 2021 13:09:55 +0800
From:   Zheyu Ma <zheyuma97@...il.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     cernekee@...il.com, jirislaby@...nel.org,
        linux-serial@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] serial: rp2: disable interrupt in rp2_probe():

On Thu, May 20, 2021 at 10:30 PM Greg KH <gregkh@...uxfoundation.org> wrote:
>
> On Fri, May 14, 2021 at 11:17:07AM +0000, Zheyu Ma wrote:
> > In 'rp2_probe', the driver registers 'rp2_uart_interrupt' then calls
> > 'rp2_fw_cb' through 'request_firmware_nowait'. In 'rp2_fw_cb', if the
> > firmware don't exists, function just return without initializing ports
> > of 'rp2_card'. But now the interrupt handler function has been registered,
> > and when an interrupt comes('rp2' may shares an interrupt line with other
> > devices), 'rp2_uart_interrupt' may access those ports then causing NULL
> > pointer dereference or other bugs.
> >
> > Fix this by disabling interrupt after registering 'rp2_uart_interrupt',
> > and enable it in 'rp2_uart_startup'.
>
> What prevents an interrupt from coming in right after callin
> rp2_uart_interrupt()?  The driver has to be able to handle that.  Why is
> the interrupt being registered before the firmware is loaded?  That
> should be the proper fix as once you register an interrupt, the driver
> HAS to be able to properly handle it.
>
> thanks,
>
> greg k-h

Thanks for your comments, I will reconsider this patch and send the
second version of the patch.

Zheyu Ma