linux-kernel - RE: [PATCH 2/2] tty: serial: fsl_lpuart: fix the potential bug of dereference null return value

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Date:   Mon, 26 Apr 2021 12:46:47 +0000
From:   Sherry Sun <sherry.sun@....com>
To:     Greg KH <gregkh@...uxfoundation.org>
CC:     "jirislaby@...nel.org" <jirislaby@...nel.org>,
        "linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        dl-linux-imx <linux-imx@....com>
Subject: RE: [PATCH 2/2] tty: serial: fsl_lpuart: fix the potential bug of
 dereference null return value


Hi Greg,

> > Hi Greg,
> >
> > > -----Original Message-----
> > > From: Greg KH <gregkh@...uxfoundation.org>
> > > Sent: 2021年4月26日 16:09
> > > To: Sherry Sun <sherry.sun@....com>
> > > Cc: jirislaby@...nel.org; linux-serial@...r.kernel.org; linux-
> > > kernel@...r.kernel.org; dl-linux-imx <linux-imx@....com>
> > > Subject: Re: [PATCH 2/2] tty: serial: fsl_lpuart: fix the potential
> > > bug of dereference null return value
> > >
> > > On Mon, Apr 26, 2021 at 03:49:35PM +0800, Sherry Sun wrote:
> > > > This issue is reported by Coverity Check.
> > > > In lpuart_probe, return value of function which returns null is
> > > > dereferenced without checking.
> > > >
> > > > Signed-off-by: Sherry Sun <sherry.sun@....com>
> > > > ---
> > > >  drivers/tty/serial/fsl_lpuart.c | 3 +++
> > > >  1 file changed, 3 insertions(+)
> > > >
> > > > diff --git a/drivers/tty/serial/fsl_lpuart.c
> > > > b/drivers/tty/serial/fsl_lpuart.c index 777d54b593f8..c95e71fd2ca0
> > > > 100644
> > > > --- a/drivers/tty/serial/fsl_lpuart.c
> > > > +++ b/drivers/tty/serial/fsl_lpuart.c
> > > > @@ -2589,6 +2589,9 @@ static int lpuart_probe(struct
> > > > platform_device
> > > *pdev)
> > > >  	struct resource *res;
> > > >  	int ret;
> > > >
> > > > +	if (!sdata)
> > > > +		return -ENODEV;
> > >
> > > How can sdata be NULL?
> >
> > Is it possible that a case forgot to set sdata? Then the value will be NULL,
> such as { .compatible = "fsl,imx8qxp-lpuart",  }.
> 
> If a case forgets to set that somehow, then the driver will never work with
> that kernel change, so someone better not submit that update :)
> 
> No need to check for something that is impossible to hit.

Okay, got it, will drop this patch, thanks!

Best regards
Sherry
> 
> thanks,
> 
> greg k-h