Set TPM_CHIP_FLAG_SUSPENDED in tpm_pm_suspend() and reset in
tpm_pm_resume(). While the flag is set, tpm_hwrng() gives back zero
bytes. This prevents hwrng from racing during resume.
Cc: stable@vger.kernel.org
Fixes:
6e592a065d51 ("tpm: Move Linux RNG connection to hwrng")
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
{
struct tpm_chip *chip = container_of(rng, struct tpm_chip, hwrng);
+ /* Give back zero bytes, as TPM chip has not yet fully resumed: */
+ if (chip->flags & TPM_CHIP_FLAG_SUSPENDED)
+ return 0;
+
return tpm_get_random(chip, data, max);
}
}
suspended:
+ chip->flags |= TPM_CHIP_FLAG_SUSPENDED;
+
if (rc)
dev_err(dev, "Ignoring error %d while suspending\n", rc);
return 0;
if (chip == NULL)
return -ENODEV;
+ chip->flags &= ~TPM_CHIP_FLAG_SUSPENDED;
+
+ /*
+ * Guarantee that SUSPENDED is written last, so that hwrng does not
+ * activate before the chip has been fully resumed.
+ */
+ wmb();
+
return 0;
}
EXPORT_SYMBOL_GPL(tpm_pm_resume);
TPM_CHIP_FLAG_ALWAYS_POWERED = BIT(5),
TPM_CHIP_FLAG_FIRMWARE_POWER_MANAGED = BIT(6),
TPM_CHIP_FLAG_FIRMWARE_UPGRADE = BIT(7),
+ TPM_CHIP_FLAG_SUSPENDED = BIT(8),
};
#define to_tpm_chip(d) container_of(d, struct tpm_chip, dev)