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| author | Jarkko Sakkinen <jarkko@kernel.org> | 2023-04-26 20:29:28 +0300 |
|---|---|---|
| committer | Jarkko Sakkinen <jarkko@kernel.org> | 2023-05-16 02:43:12 +0300 |
| commit | 99d46450625590d410f86fe4660a5eff7d3b8343 (patch) | |
| tree | 446c3d6a59c7a4a8762954ee3e527ff0b257d686 /drivers/char/tpm | |
| parent | 1398aa803f198b7a386fdd8404666043e95f4c16 (diff) | |
| download | linux-99d46450625590d410f86fe4660a5eff7d3b8343.tar.gz | |
tpm: Prevent hwrng from activating during resume
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>
Diffstat (limited to 'drivers/char/tpm')
| -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 c10a4aa973736..cd48033b804a3 100644 --- a/drivers/char/tpm/tpm-chip.c +++ b/drivers/char/tpm/tpm-chip.c @@ -571,6 +571,10 @@ 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 4463d00182909..586ca10b0d72e 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); |