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Date: Wed, 7 Feb 2024 14:12:53 +0530
From: Dhruva Gole <d-gole@ti.com>
To: =?utf-8?B?VGjDqW8=?= Lebrun <theo.lebrun@bootlin.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
Message-ID: <20240207084253.fxrnoskda5x6usqo@dhruva>
References: <20240205-cdns-qspi-pm-fix-v2-0-2e7bbad49a46@bootlin.com>
 <20240205-cdns-qspi-pm-fix-v2-2-2e7bbad49a46@bootlin.com>
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In-Reply-To: <20240205-cdns-qspi-pm-fix-v2-2-2e7bbad49a46@bootlin.com>

On Feb 05, 2024 at 15:57:30 +0100, Th?o 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: Th?o 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;

>  	int ret;
>  
> -	ret = spi_controller_suspend(host);
> +	ret = spi_controller_suspend(cqspi->host);

And avoid changing these?

>  	cqspi_controller_enable(cqspi, 0);
>  
>  	clk_disable_unprepare(cqspi->clk);
> @@ -1944,7 +1943,6 @@ static int cqspi_runtime_suspend(struct device *dev)
>  static int cqspi_runtime_resume(struct device *dev)
>  {
>  	struct cqspi_st *cqspi = dev_get_drvdata(dev);
> -	struct spi_controller *host = dev_get_drvdata(dev);
>  
>  	clk_prepare_enable(cqspi->clk);
>  	cqspi_wait_idle(cqspi);
> @@ -1953,7 +1951,7 @@ static int cqspi_runtime_resume(struct device *dev)
>  	cqspi->current_cs = -1;
>  	cqspi->sclk = 0;
>  
> -	return spi_controller_resume(host);
> +	return spi_controller_resume(cqspi->host);

ditto.

Thanks,
Dhruva Gole <d-gole@ti.com>

>  }
>  
>  static DEFINE_RUNTIME_DEV_PM_OPS(cqspi_dev_pm_ops, cqspi_runtime_suspend,
> 
> -- 
> 2.43.0
> 
>