RE: [PATCH] remoteproc: imx_rproc: validate resource table

From: Peng Fan <peng.fan@nxp.com>
To: Mathieu Poirier <mathieu.poirier@linaro.org>,
	"Peng Fan (OSS)" <peng.fan@oss.nxp.com>
Cc: "bjorn.andersson@linaro.org" <bjorn.andersson@linaro.org>,
	"shawnguo@kernel.org" <shawnguo@kernel.org>,
	"s.hauer@pengutronix.de" <s.hauer@pengutronix.de>,
	"kernel@pengutronix.de" <kernel@pengutronix.de>,
	"festevam@gmail.com" <festevam@gmail.com>,
	dl-linux-imx <linux-imx@nxp.com>,
	"linux-remoteproc@vger.kernel.org"
	<linux-remoteproc@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH] remoteproc: imx_rproc: validate resource table
Date: Tue, 18 Jan 2022 01:24:38 +0000	[thread overview]
Message-ID: <DU0PR04MB9417BEA67ED9C2185C5C874A88589@DU0PR04MB9417.eurprd04.prod.outlook.com> (raw)
In-Reply-To: <20220117182551.GC1119324@p14s>

> Subject: Re: [PATCH] remoteproc: imx_rproc: validate resource table
> 
> Good morning,
> 
> On Tue, Jan 11, 2022 at 11:33:23AM +0800, Peng Fan (OSS) wrote:
> > From: Peng Fan <peng.fan@nxp.com>
> >
> > Currently NXP use one device tree to support all NXP released Cortex-M
> > demos. There is one simple demo that not need to communicate with
> > Linux, thus it will not update the resource table. So there maybe
> > garbage data in it. In such case, Linux should directly ignore it.
> >
> > It is hard to decide what data is garbage data, NXP released SDK use
> > ver(1), reserved(0) in a valid resource table. But in case others use
> > different value, so here use 0xff as a max value for ver and num.
> >
> > Signed-off-by: Peng Fan <peng.fan@nxp.com>
> > ---
> >  drivers/remoteproc/imx_rproc.c | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> >
> > diff --git a/drivers/remoteproc/imx_rproc.c
> > b/drivers/remoteproc/imx_rproc.c index 0bd24c937a73..75fde16f80a4
> > 100644
> > --- a/drivers/remoteproc/imx_rproc.c
> > +++ b/drivers/remoteproc/imx_rproc.c
> > @@ -490,11 +490,19 @@ static int imx_rproc_attach(struct rproc *rproc)
> > static struct resource_table *imx_rproc_get_loaded_rsc_table(struct
> > rproc *rproc, size_t *table_sz)  {
> >  	struct imx_rproc *priv = rproc->priv;
> > +	struct resource_table *table;
> >
> >  	/* The resource table has already been mapped in imx_rproc_addr_init
> */
> >  	if (!priv->rsc_table)
> >  		return NULL;
> >
> > +	table = priv->rsc_table;
> > +	/* Gabage data check */
> > +	if (table->ver >= 0xff || table->num >= 0xff || table->reserved[0] ||
> table->reserved[1]) {
> > +		dev_err(priv->dev, "Ignore invalid rsc table\n");
> > +		return NULL;
> > +	}
> > +
> 
> This seems like the wrong fix to me.  Either use different DTs or update the
> resource table for all demos - efficiency should not be a problem since they
> are demos.  With the above it is only a matter of time before the pattern
> associated with valid resource tables changes, leading to more hacks that will
> be impossible to maintain over time.

I see, drop this patch :)

Thanks,
Peng.

> 
> Thanks,
> Mathieu
> 
> >  	*table_sz = SZ_1K;
> >  	return (struct resource_table *)priv->rsc_table;  }
> > --
> > 2.25.1
> >