diff options
| author | Jarkko Sakkinen <jarkko@kernel.org> | 2023-04-26 20:29:28 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-05-30 16:03:16 +0300 |
| commit | 7cd46930b8bf37b84777410ac21bfdf1179021d5 (patch) | |
| tree | c453feb0fe67e32e194e6291d6f029751df5a2c8 /drivers/char | |
| parent | 25d38d5eaa1f7a4d8075d23633f1722b38c8c7a7 (diff) | |
| download | linux-7cd46930b8bf37b84777410ac21bfdf1179021d5.tar.xz | |
tpm: Prevent hwrng from activating during resume
[ Upstream commit 99d46450625590d410f86fe4660a5eff7d3b8343 ]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'drivers/char')
| -rw-r--r-- | drivers/char/tpm/tpm-chip.c | 4 | ||||
| -rw-r--r-- | drivers/char/tpm/tpm-interface.c | 10 |
2 files changed, 14 insertions, 0 deletions
diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c index 31d807482152..95d847c9de79 100644 --- a/drivers/char/tpm/tpm-chip.c +++ b/drivers/char/tpm/tpm-chip.c @@ -568,6 +568,10 @@ 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 7e513b771832..0f941cb32eb1 100644 --- a/drivers/char/tpm/tpm-interface.c +++ b/drivers/char/tpm/tpm-interface.c @@ -412,6 +412,8 @@ int tpm_pm_suspend(struct device *dev) } suspended: + chip->flags |= TPM_CHIP_FLAG_SUSPENDED; + if (rc) dev_err(dev, "Ignoring error %d while suspending\n", rc); return 0; @@ -429,6 +431,14 @@ int tpm_pm_resume(struct device *dev) 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); |