TPM: integrity fix

Fix to function which is called by IMA, now tpm_chip_find_get() considers the case in which the machine doesn't have a TPM or, if it has, its TPM isn't enabled.

Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Rajiv Andrade <srajiv@linux.vnet.ibm.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 5 insertions, 3 deletions

diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c
index 62a5682578ca..ccdd828adcef 100644
--- a/drivers/char/tpm/tpm.c
+++ b/drivers/char/tpm/tpm.c
@@ -666,18 +666,20 @@ EXPORT_SYMBOL_GPL(tpm_show_temp_deactivated);
  */
 static struct tpm_chip *tpm_chip_find_get(int chip_num)
 {
-        struct tpm_chip *pos;
+        struct tpm_chip *pos, *chip = NULL;
 
         rcu_read_lock();
         list_for_each_entry_rcu(pos, &tpm_chip_list, list) {
                 if (chip_num != TPM_ANY_NUM && chip_num != pos->dev_num)
                         continue;
 
-                if (try_module_get(pos->dev->driver->owner))
+                if (try_module_get(pos->dev->driver->owner)) {
+                        chip = pos;
                         break;
+                }
         }
         rcu_read_unlock();
-        return pos;
+        return chip;
 }
 
 #define TPM_ORDINAL_PCRREAD cpu_to_be32(21)