Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH] tpm: fix potential NULL pointer access in
 tpm_del_char_device()
To:     Jason Gunthorpe <jgg@ziepe.ca>
Cc:     Jarkko Sakkinen <jarkko@kernel.org>, peterhuewe@gmx.de,
        p.rosenberger@kunbus.com, linux-integrity@vger.kernel.org,
        linux-kernel@vger.kernel.org, stable@vger.kernel.org
References: <20210910180451.19314-1-LinoSanfilippo@gmx.de>
 <204a438b6db54060d03689389d6663b0d4ca815d.camel@kernel.org>
 <trinity-27f56ffd-504a-4c34-9cda-0953ccc459a3-1631566430623@3c-app-gmx-bs69>
 <c22d2878f9816000c33f5349e7256cadae22b400.camel@kernel.org>
 <50bd6224-0f01-ca50-af0e-f79b933e7998@gmx.de>
 <20210924133321.GX3544071@ziepe.ca>
From:   Lino Sanfilippo <LinoSanfilippo@gmx.de>
Message-ID: <b49f4b52-44c4-8cb8-a102-689e9f788177@gmx.de>
Date:   Fri, 24 Sep 2021 16:17:52 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.10.0
MIME-Version: 1.0
In-Reply-To: <20210924133321.GX3544071@ziepe.ca>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

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 i=
s 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 =3D bcm2835_spi_remove(pdev);
	if (ret)
		dev_err(&pdev->dev, "failed to shutdown\n");
}


Regards,
Lino