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

Jarkko Sakkinen
2015-11-08T07:51:57Z

__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