Merge tag 'tpmdd-next-6.12-rc7' of git://git.kernel.org/pub/scm/linux…

…/kernel/git/jarkko/linux-tpmdd Pull tpm fix from Jarkko Sakkinen: "Fix a race condition between tpm_pm_suspend() and tpm_hwrng_read() (I think for good now)" * tag 'tpmdd-next-6.12-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-tpmdd: tpm: Lock TPM chip in tpm_pm_suspend() first
K900 · Nov 4, 2024 · a033940 · a033940
2 parents 59b723c + 9265fed
commit a033940
Show file tree

Hide file tree

Showing 2 changed files with 22 additions and 14 deletions.
diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
@@ -525,10 +525,6 @@ static int tpm_hwrng_read(struct hwrng *rng, void *data, size_t max, bool wait)
 {
 	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);
 }
 

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
@@ -370,28 +370,33 @@ int tpm_pm_suspend(struct device *dev)
 	if (!chip)
 		return -ENODEV;
 
+	rc = tpm_try_get_ops(chip);
+	if (rc) {
+		/* Can be safely set out of locks, as no action cannot race: */
+		chip->flags |= TPM_CHIP_FLAG_SUSPENDED;
+		goto out;
+	}
+
 	if (chip->flags & TPM_CHIP_FLAG_ALWAYS_POWERED)
 		goto suspended;
 
 	if ((chip->flags & TPM_CHIP_FLAG_FIRMWARE_POWER_MANAGED) &&
 	    !pm_suspend_via_firmware())
 		goto suspended;
 
-	rc = tpm_try_get_ops(chip);
-	if (!rc) {
-		if (chip->flags & TPM_CHIP_FLAG_TPM2) {
-			tpm2_end_auth_session(chip);
-			tpm2_shutdown(chip, TPM2_SU_STATE);
-		} else {
-			rc = tpm1_pm_suspend(chip, tpm_suspend_pcr);
-		}
-
-		tpm_put_ops(chip);
+	if (chip->flags & TPM_CHIP_FLAG_TPM2) {
+		tpm2_end_auth_session(chip);
+		tpm2_shutdown(chip, TPM2_SU_STATE);
+		goto suspended;
 	}
 
+	rc = tpm1_pm_suspend(chip, tpm_suspend_pcr);
+
 suspended:
 	chip->flags |= TPM_CHIP_FLAG_SUSPENDED;
+	tpm_put_ops(chip);
 
+out:
 	if (rc)
 		dev_err(dev, "Ignoring error %d while suspending\n", rc);
 	return 0;
@@ -440,11 +445,18 @@ int tpm_get_random(struct tpm_chip *chip, u8 *out, size_t max)
 	if (!chip)
 		return -ENODEV;
 
+	/* Give back zero bytes, as TPM chip has not yet fully resumed: */
+	if (chip->flags & TPM_CHIP_FLAG_SUSPENDED) {
+		rc = 0;
+		goto out;
+	}
+
 	if (chip->flags & TPM_CHIP_FLAG_TPM2)
 		rc = tpm2_get_random(chip, out, max);
 	else
 		rc = tpm1_get_random(chip, out, max);
 
+out:
 	tpm_put_ops(chip);
 	return rc;
 }