From: Jarkko Sakkinen jarkko@kernel.org

[ Upstream commit 9265fed6db601ee2ec47577815387458ef4f047a ]

Setting TPM_CHIP_FLAG_SUSPENDED in the end of tpm_pm_suspend() can be racy according, as this leaves window for tpm_hwrng_read() to be called while the operation is in progress. The recent bug report gives also evidence of this behaviour.

Aadress this by locking the TPM chip before checking any chip->flags both in tpm_pm_suspend() and tpm_hwrng_read(). Move TPM_CHIP_FLAG_SUSPENDED check inside tpm_get_random() so that it will be always checked only when the lock is reserved.

Cc: stable@vger.kernel.org # v6.4+ Fixes: 99d464506255 ("tpm: Prevent hwrng from activating during resume") Reported-by: Mike Seo mikeseohyungjin@gmail.com Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219383 Reviewed-by: Jerry Snitselaar jsnitsel@redhat.com Tested-by: Mike Seo mikeseohyungjin@gmail.com Signed-off-by: Jarkko Sakkinen jarkko@kernel.org [ Don't call tpm2_end_auth_session() for this function does not exist in 6.6.y.] Signed-off-by: Bin Lan bin.lan.cn@windriver.com --- drivers/char/tpm/tpm-chip.c | 4 ---- drivers/char/tpm/tpm-interface.c | 29 +++++++++++++++++++++-------- 2 files changed, 21 insertions(+), 12 deletions(-)

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c index 42b1062e33cd..78999f7f248c 100644 --- a/drivers/char/tpm/tpm-chip.c +++ b/drivers/char/tpm/tpm-chip.c @@ -519,10 +519,6 @@ 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 index 66b16d26eecc..c8ea52dfa556 100644 --- a/drivers/char/tpm/tpm-interface.c +++ b/drivers/char/tpm/tpm-interface.c @@ -394,6 +394,13 @@ 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;

@@ -401,19 +408,18 @@ int tpm_pm_suspend(struct device *dev) !pm_suspend_via_firmware()) goto suspended;

- rc = tpm_try_get_ops(chip); - if (!rc) { - if (chip->flags & TPM_CHIP_FLAG_TPM2) - 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_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; @@ -462,11 +468,18 @@ 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; }