Re: [PATCH 4.19 002/106] tpm: Fix TPM 1.2 Shutdown sequence to prevent future TPM operations

Hi!

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.

...

--- a/drivers/char/tpm/tpm-chip.c +++ b/drivers/char/tpm/tpm-chip.c @@ -187,12 +187,13 @@ 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);

return 0; }

Still can be improved -- chip->ops = NULL; is done twice, copy inside the if {} is redundant...

Best regards, Pavel