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

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

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@...tlin.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