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    SubjectRe: [PATCH 4.19 33/63] tpm: Fix TPM 1.2 Shutdown sequence to prevent future TPM operations
    On Mon, Sep 30, 2019 at 08:13:46AM +0200, Pavel Machek wrote:
    >> From: Vadim Sukhomlinov <sukhomlinov@google.com>
    >>
    >> commit db4d8cb9c9f2af71c4d087817160d866ed572cc9 upstream
    >>
    >> TPM 2.0 Shutdown involve sending TPM2_Shutdown to TPM chip and disabling
    >> future TPM operations. TPM 1.2 behavior was different, future TPM
    >> operations weren't disabled, causing rare issues. This patch ensures
    >> that future TPM operations are disabled.
    >
    >> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
    >> index 46caadca916a0..dccc61af9ffab 100644
    >> --- a/drivers/char/tpm/tpm-chip.c
    >> +++ b/drivers/char/tpm/tpm-chip.c
    >> @@ -187,12 +187,15 @@ static int tpm_class_shutdown(struct device *dev)
    >> {
    >> struct tpm_chip *chip = container_of(dev, struct tpm_chip, dev);
    >>
    >> + down_write(&chip->ops_sem);
    >> if (chip->flags & TPM_CHIP_FLAG_TPM2) {
    >> down_write(&chip->ops_sem);
    >> tpm2_shutdown(chip, TPM2_SU_CLEAR);
    >> chip->ops = NULL;
    >> up_write(&chip->ops_sem);
    >> }
    >> + chip->ops = NULL;
    >> + up_write(&chip->ops_sem);
    >
    >This is wrong, it takes &chip->ops_sem twice, that can't be
    >good. db4d8cb9c9f2af71c4d087817160d866ed572cc9 does not have that
    >problem.

    I agree. I've dropped it from 4.19 and 4.14.

    Jarkko, can you take a look at this again please?

    --
    Thanks,
    Sasha

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