Re: [PATCH] tpm: fix compat 'ppi' link handling in tpm_chip_register()

Jeremiah Mahler
2015-11-10T06:11:45Z

Jarkko,

On Sun, Nov 08, 2015 at 09:51:07AM +0200, Jarkko Sakkinen wrote:
> __compat_only_sysfs_link_entry_to_kobj() was unconditionally called for
> TPM1 chips, which caused crash on Acer C720 laptop where DSM for the
> ACPI object did not exist.
>
> There are two reasons for unwanted behavior:
>
> * The code did not check whether
> __compat_only_sysfs_link_entry_to_kobj() returned -ENOENT. This is
> OK. It just meanst that ppi is not available.
> * The code did not clean up properly. Compat link should added only
> after all other init is done.
>
> This patch sorts out these issues.
>
> Fixes: 9b774d5cf2db
> Reported-by: Jeremiah Mahler <jmmahler@gmail.com>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> Tested-by: Jeremiah Mahler <jmmahler@gmail.com>
> ---
> drivers/char/tpm/tpm-chip.c | 18 ++++++++++--------
> 1 file changed, 10 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> index a5cdce7..45cc39a 100644
> --- a/drivers/char/tpm/tpm-chip.c
> +++ b/drivers/char/tpm/tpm-chip.c
> @@ -226,14 +226,6 @@ int tpm_chip_register(struct tpm_chip *chip)
> if (rc)
> goto out_err;
>
> - if (!(chip->flags & TPM_CHIP_FLAG_TPM2)) {
> - rc = __compat_only_sysfs_link_entry_to_kobj(&chip->pdev->kobj,
> - &chip->dev.kobj,
> - "ppi");
> - if (rc)
> - goto out_err;
> - }
> -
> /* Make the chip available. */
> spin_lock(&driver_lock);
> list_add_tail_rcu(&chip->list, &tpm_chip_list);
> @@ -241,6 +233,16 @@ int tpm_chip_register(struct tpm_chip *chip)
>
> chip->flags |= TPM_CHIP_FLAG_REGISTERED;
>
> + if (!(chip->flags & TPM_CHIP_FLAG_TPM2)) {
> + rc = __compat_only_sysfs_link_entry_to_kobj(&chip->pdev->kobj,
> + &chip->dev.kobj,
> + "ppi");
> + if (rc && rc != -ENOENT) {
> + tpm_chip_unregister(chip);
> + return rc;
> + }
> + }
> +
> return 0;
> out_err:
> tpm1_chip_unregister(chip);
> --
> 2.5.0
>

This patch doesn't apply to the latest linux-next (20151109). I think I
may be missing a dependent patch. Do you know which one?

--
- Jeremiah Mahler