From: Jarkko Sakkinen <jarkko@kernel.org>
To: amirmizi6@gmail.com, Eyal.Cohen@nuvoton.com,
oshrialkoby85@gmail.com, alexander.steffen@infineon.com,
robh+dt@kernel.org, mark.rutland@arm.com, peterhuewe@gmx.de,
jgg@ziepe.ca, arnd@arndb.de, gregkh@linuxfoundation.org,
benoit.houyere@st.com, eajames@linux.ibm.com, joel@jms.id.au
Cc: devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-integrity@vger.kernel.org, oshri.alkoby@nuvoton.com,
tmaimon77@gmail.com, gcwilson@us.ibm.com, kgoldman@us.ibm.com,
Dan.Morav@nuvoton.com, oren.tanami@nuvoton.com,
shmulik.hager@nuvoton.com, amir.mizinski@nuvoton.com
Subject: Re: [PATCH v19 3/5] tpm: tpm_tis: Verify TPM_STS register is valid after locality request
Date: Wed, 17 Nov 2021 10:10:36 +0200 [thread overview]
Message-ID: <a13a7e60a25bcdfc186d9b262f21947ca4e0159e.camel@kernel.org> (raw)
In-Reply-To: <20211104140211.6258-4-amirmizi6@gmail.com>
On Thu, 2021-11-04 at 16:02 +0200, amirmizi6@gmail.com wrote:
> From: Amir Mizinski <amirmizi6@gmail.com>
>
> An invalid TPM_STS value could be used when the following two events occur:
> TPM does not update TPM_STS register after a locality request (TPM_STS
> Initial value = 0xFF), and a TPM_STS register read occurs in the
> tpm_tis_status(chip) function call.
>
> In probe_itpm(), a call to tpm_tis_send_data() function is made after a
> request_locality() call, and the condition
> ("if ((status & TPM_STS_COMMAND_READY) == 0)") is checked. At this moment
> if the status value is 0xFF, then it is considered, wrongly, in “ready”
> state (by checking only one bit). However, at this moment the TPM is, in
> fact, in "Idle" state and remains in "Idle" state because
> "tpm_tis_ready(chip);" was not executed.
> Waiting for the condition TPM_STS.tpmGo == 0, will ensure that the TPM
> status register has the correct value.
You should use imperative form in commit message, e.g. "Wait for TPM_STS.tpmGo
to reset to zero, ...".
>
> Suggested-by: Benoit Houyere <benoit.houyere@st.com>
> Signed-off-by: Amir Mizinski <amirmizi6@gmail.com>
> ---
> drivers/char/tpm/tpm_tis_core.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> index 6ff8b44..770685a 100644
> --- a/drivers/char/tpm/tpm_tis_core.c
> +++ b/drivers/char/tpm/tpm_tis_core.c
> @@ -177,8 +177,12 @@ static int request_locality(struct tpm_chip *chip, int l)
> } else {
> /* wait for burstcount */
> do {
> - if (check_locality(chip, l))
> + if (check_locality(chip, l)) {
> + if (tpm_tis_wait_for_stat(chip, TPM_STS_GO, 0, chip->timeout_c,
> + &priv->int_queue, false) < 0)
You would need to explain this with an inline comment.
> + return -ETIME;
> return l;
> + }
> tpm_msleep(TPM_TIMEOUT);
> } while (time_before(jiffies, stop));
> }
/Jarkko
next prev parent reply other threads:[~2021-11-17 8:10 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-04 14:02 [PATCH v19 0/5] Add tpm i2c ptp driver amirmizi6
2021-11-04 14:02 ` [PATCH v19 1/5] tpm_tis: Fix expected bit handling amirmizi6
2021-11-04 14:02 ` [PATCH v19 2/5] tpm: tpm_tis: Rewrite "tpm_tis_req_canceled()" amirmizi6
2021-11-17 8:03 ` Jarkko Sakkinen
2021-11-04 14:02 ` [PATCH v19 3/5] tpm: tpm_tis: Verify TPM_STS register is valid after locality request amirmizi6
2021-11-17 8:10 ` Jarkko Sakkinen
2021-11-17 8:10 ` Jarkko Sakkinen [this message]
2021-11-04 14:02 ` [PATCH v19 4/5] tpm: tpm_tis: Add tpm_tis_i2c driver amirmizi6
2021-11-17 8:19 ` Jarkko Sakkinen
2022-01-14 4:12 ` Joel Stanley
2021-11-04 14:02 ` [PATCH v19 5/5] tpm: Add YAML schema for TPM TIS I2C options amirmizi6
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