linux-kernel - Re: [PATCH 2/2] serial: 8250: dw: Fix NULL pointer dereference

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Date:   Wed, 29 Jun 2022 11:01:11 +0300 (EEST)
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     Jeremy Linton <jeremy.linton@....com>
cc:     linux-serial <linux-serial@...r.kernel.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>, miquel.raynal@...tlin.com,
        phil.edworthy@...esas.com, kernel@...il.dk,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] serial: 8250: dw: Fix NULL pointer dereference

Hi,

Does cd16044d7c38 ("serial: 8250: dw: enable using pdata with ACPI") work 
for you? (Currently in tty-linus branch).

-- 
 i.


On Tue, 28 Jun 2022, Jeremy Linton wrote:

> Similarly to e6a08c6949cb, ACPI machines don't have
> a pdata setup, leading to a null pointer dereference
> when dw8250_handle_irq runs.
> 
> Fixes: aa63d786cea2 ("serial: 8250: dw: Add support for DMA flow controlling devices")
> Signed-off-by: Jeremy Linton <jeremy.linton@....com>
> ---
>  drivers/tty/serial/8250/8250_dw.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
> index 53e488beb8c2..06f80090cbb9 100644
> --- a/drivers/tty/serial/8250/8250_dw.c
> +++ b/drivers/tty/serial/8250/8250_dw.c
> @@ -237,10 +237,13 @@ static int dw8250_handle_irq(struct uart_port *p)
>  	struct dw8250_data *d = to_dw8250_data(p->private_data);
>  	unsigned int iir = p->serial_in(p, UART_IIR);
>  	bool rx_timeout = (iir & 0x3f) == UART_IIR_RX_TIMEOUT;
> -	unsigned int quirks = d->pdata->quirks;
> +	unsigned int quirks = 0;
>  	unsigned int status;
>  	unsigned long flags;
>  
> +	if (d->pdata)
> +		quirks = d->pdata->quirks;
> +
>  	/*
>  	 * There are ways to get Designware-based UARTs into a state where
>  	 * they are asserting UART_IIR_RX_TIMEOUT but there is no actual
>