linux-kernel - Re: [PATCH] tpm: fix potential NULL pointer access in tpm_del_char

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Date:   Fri, 24 Sep 2021 16:17:52 +0200
From:   Lino Sanfilippo <LinoSanfilippo@....de>
To:     Jason Gunthorpe <jgg@...pe.ca>
Cc:     Jarkko Sakkinen <jarkko@...nel.org>, peterhuewe@....de,
        p.rosenberger@...bus.com, linux-integrity@...r.kernel.org,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] tpm: fix potential NULL pointer access in
 tpm_del_char_device()

On 24.09.21 at 15:33, Jason Gunthorpe wrote:
> On Fri, Sep 24, 2021 at 03:29:46PM +0200, Lino Sanfilippo wrote:
>
>> So this bug is triggered when the bcm2835 drivers shutdown() function is called since this
>> driver does something quite unusual: it unregisters the spi controller in its shutdown()
>> handler.
>
> This seems wrong
>
> Jason
>


Unregistering the SPI controller during shutdown is only a side-effect of calling
bcm2835_spi_remove() in the shutdown handler:

static void bcm2835_spi_shutdown(struct platform_device *pdev)
{
	int ret;

	ret = bcm2835_spi_remove(pdev);
	if (ret)
		dev_err(&pdev->dev, "failed to shutdown\n");
}


Regards,
Lino