linux-kernel - Re: [PATCH v3 2/2] tpm: in tpm2_del_space check if ops pointer is still valid

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Date:   Fri, 5 Feb 2021 07:51:02 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Lino Sanfilippo <LinoSanfilippo@....de>
Cc:     peterhuewe@....de, jarkko@...nel.org, jgg@...pe.ca,
        stefanb@...ux.vnet.ibm.com, James.Bottomley@...senpartnership.com,
        stable@...r.kernel.org, linux-integrity@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Lino Sanfilippo <l.sanfilippo@...bus.com>
Subject: Re: [PATCH v3 2/2] tpm: in tpm2_del_space check if ops pointer is
 still valid

On Fri, Feb 05, 2021 at 12:50:43AM +0100, Lino Sanfilippo wrote:
> From: Lino Sanfilippo <l.sanfilippo@...bus.com>
> 
> In tpm2_del_space() chip->ops is used for flushing the sessions. However
> this function may be called after tpm_chip_unregister() which sets
> the chip->ops pointer to NULL.
> Avoid a possible NULL pointer dereference by checking if chip->ops is still
> valid before accessing it.
> 
> Fixes: a3fbfae82b4c ("tpm: take TPM chip power gating out of tpm_transmit()")
> Signed-off-by: Lino Sanfilippo <l.sanfilippo@...bus.com>
> ---
>  drivers/char/tpm/tpm2-space.c | 15 ++++++++++-----
>  1 file changed, 10 insertions(+), 5 deletions(-)

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>