linux-kernel - Re: [PATCH 2/2] usb: typec: tipd: Add an additional overflow check

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Message-Id: <05fe66fe-e1a3-46ba-bbd6-8b0a41109b81@www.fastmail.com>
Date:   Tue, 14 Sep 2021 13:18:16 +0200
From:   "Sven Peter" <sven@...npeter.dev>
To:     "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>
Cc:     "Heikki Krogerus" <heikki.krogerus@...ux.intel.com>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] usb: typec: tipd: Add an additional overflow check



On Tue, Sep 14, 2021, at 13:00, Greg Kroah-Hartman wrote:
> On Tue, Sep 14, 2021 at 12:42:53PM +0200, Sven Peter wrote:
> > tps6598x_block_read already checks for the maximum length of the read
> > but tps6598x_block_write does not. Add the symmetric check there as
> > well.
> > 
> > Signed-off-by: Sven Peter <sven@...npeter.dev>
> > ---
> >  drivers/usb/typec/tipd/core.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/drivers/usb/typec/tipd/core.c b/drivers/usb/typec/tipd/core.c
> > index c18ec3785592..70e2d0d410c9 100644
> > --- a/drivers/usb/typec/tipd/core.c
> > +++ b/drivers/usb/typec/tipd/core.c
> > @@ -139,6 +139,9 @@ static int tps6598x_block_write(struct tps6598x *tps, u8 reg,
> >  {
> >  	u8 data[TPS_MAX_LEN + 1];
> >  
> > +	if (WARN_ON(len + 1 > sizeof(data)))
> > +		return -EINVAL;
> 
> No need to crash anything.  If this is a valid thing for us to check,
> let's check it and handle the error, but we should not reboot systems
> that are running with panic-on-warn enabled, right?

Sure, that makes sense. I guess the same point applies to the WARN_ON in
the same check in tps6598x_block_read. I can add a patch to remove that one
to v2 as well.


thanks,


Sven