From: Jarkko Sakkinen <jarkko@kernel.org>
To: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Cc: peterhuewe@gmx.de, jgg@ziepe.ca, stefanb@linux.vnet.ibm.com,
linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org,
Lino Sanfilippo <l.sanfilippo@kunbus.com>
Subject: Re: [PATCH v2 3/3] tpm: in tpm2_del_space check if ops pointer is still valid
Date: Wed, 3 Feb 2021 03:17:07 +0200 [thread overview]
Message-ID: <YBn5kwEIoggc71xY@kernel.org> (raw)
In-Reply-To: <1612303743-29017-4-git-send-email-LinoSanfilippo@gmx.de>
On Tue, Feb 02, 2021 at 11:09:03PM +0100, Lino Sanfilippo wrote:
> From: Lino Sanfilippo <l.sanfilippo@kunbus.com>
>
> In tpm2_del_space() the sessions are flushed by means of the tpm_chip
> operations. However the concerning operations pointer my already be NULL at
~~
may
What is "concerniog operations"? Unfamiliar term. Maybe just consistently
se chip->ops? Now you have also "tpm_chip operations" and chip->ops, in
addition to "concerning operations" in one paragraph commit message.
> this time in case that the chip has been unregistered (see
> tpm_chip_unregister() which calls tpm_del_char_device() which sets
> chip->ops to NULL).
> Before accessing chip->ops check if it is still valid. Skip flushing
> the sessions in this case.
>
> Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
Instead of cross referencing please describe the scenario (i.e.
the sequence of operations) of failure.
Fixes tag is also missing.
> ---
> drivers/char/tpm/tpm2-space.c | 15 ++++++++++-----
> 1 file changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm2-space.c b/drivers/char/tpm/tpm2-space.c
> index 784b8b3..9a29a40 100644
> --- a/drivers/char/tpm/tpm2-space.c
> +++ b/drivers/char/tpm/tpm2-space.c
> @@ -58,12 +58,17 @@ int tpm2_init_space(struct tpm_space *space, unsigned int buf_size)
>
> void tpm2_del_space(struct tpm_chip *chip, struct tpm_space *space)
> {
> - mutex_lock(&chip->tpm_mutex);
> - if (!tpm_chip_start(chip)) {
> - tpm2_flush_sessions(chip, space);
> - tpm_chip_stop(chip);
> + down_read(&chip->ops_sem);
> + if (chip->ops) {
> + mutex_lock(&chip->tpm_mutex);
> + if (!tpm_chip_start(chip)) {
> + tpm2_flush_sessions(chip, space);
> + tpm_chip_stop(chip);
> + }
> + mutex_unlock(&chip->tpm_mutex);
> }
> - mutex_unlock(&chip->tpm_mutex);
> + up_read(&chip->ops_sem);
> +
> kfree(space->context_buf);
> kfree(space->session_buf);
> }
> --
> 2.7.4
>
/Jarkko
next prev parent reply other threads:[~2021-02-03 1:18 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-02 22:09 [PATCH v2 0/3] TPM fixes Lino Sanfilippo
2021-02-02 22:09 ` [PATCH v2 1/3] tpm: fix reference counting for struct tpm_chip Lino Sanfilippo
2021-02-03 1:09 ` Jarkko Sakkinen
2021-02-03 14:06 ` Lino Sanfilippo
2021-02-03 21:43 ` Jarkko Sakkinen
2021-02-02 22:09 ` [PATCH v2 2/3] tpm: Provide a function tpm_chip_free() to free tpm chips Lino Sanfilippo
2021-02-03 1:28 ` Jarkko Sakkinen
2021-02-03 14:09 ` Lino Sanfilippo
2021-02-02 22:09 ` [PATCH v2 3/3] tpm: in tpm2_del_space check if ops pointer is still valid Lino Sanfilippo
2021-02-03 1:17 ` Jarkko Sakkinen [this message]
2021-02-03 14:22 ` Lino Sanfilippo
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