Re: [PATCH v2 2/4] spi: cadence-qspi: fix pointer reference in runtime PM hooks

From: "Théo Lebrun" <theo.lebrun@bootlin.com>
To: "Dhruva Gole" <d-gole@ti.com>
Cc: "Mark Brown" <broonie@kernel.org>,
	"Apurva Nandan" <a-nandan@ti.com>, <linux-spi@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>,
	"Gregory CLEMENT" <gregory.clement@bootlin.com>,
	"Vladimir Kondratiev" <vladimir.kondratiev@mobileye.com>,
	"Thomas Petazzoni" <thomas.petazzoni@bootlin.com>,
	"Tawfik Bayouk" <tawfik.bayouk@mobileye.com>
Subject: Re: [PATCH v2 2/4] spi: cadence-qspi: fix pointer reference in runtime PM hooks
Date: Wed, 07 Feb 2024 10:28:59 +0100	[thread overview]
Message-ID: <CYYQOHJ4783D.39ZQKS2IK40RV@bootlin.com> (raw)
In-Reply-To: <20240207084253.fxrnoskda5x6usqo@dhruva>

Hello,

On Wed Feb 7, 2024 at 9:42 AM CET, Dhruva Gole wrote:
> On Feb 05, 2024 at 15:57:30 +0100, Théo Lebrun wrote:
> > dev_get_drvdata() gets used to acquire the pointer to cqspi and the SPI
> > controller. Neither embed the other; this lead to memory corruption.
> > 
> > On a given platform (Mobileye EyeQ5) the memory corruption is hidden
> > inside cqspi->f_pdata. Also, this uninitialised memory is used as a
> > mutex (ctlr->bus_lock_mutex) by spi_controller_suspend().
> > 
> > Fixes: 2087e85bb66e ("spi: cadence-quadspi: fix suspend-resume implementations")
> > Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
> > ---
> >  drivers/spi/spi-cadence-quadspi.c | 6 ++----
> >  1 file changed, 2 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/spi/spi-cadence-quadspi.c b/drivers/spi/spi-cadence-quadspi.c
> > index 720b28d2980c..1a27987638f0 100644
> > --- a/drivers/spi/spi-cadence-quadspi.c
> > +++ b/drivers/spi/spi-cadence-quadspi.c
> > @@ -1930,10 +1930,9 @@ static void cqspi_remove(struct platform_device *pdev)
> >  static int cqspi_runtime_suspend(struct device *dev)
> >  {
> >  	struct cqspi_st *cqspi = dev_get_drvdata(dev);
> > -	struct spi_controller *host = dev_get_drvdata(dev);
>
> Or you could do:
> +	struct spi_controller *host = cqspi->host;

Indeed. I preferred minimizing line count as I didn't see a benefit to
introducing a new variable. It goes away new patch anyway. If you
prefer it this way tell me and I'll fix it for next revision.

Thanks Dhruva,

--
Théo Lebrun, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com