[PATCH] KEYS: trusted: correctly initialize digests and fix locking issue

[Roberto Sassu]

This patch fixes two issues introduced with commit 240730437deb ("KEYS:
trusted: explicitly use tpm_chip structure from tpm_default_chip()").

It initializes the algorithm in init_digests() for trusted keys, and moves
the algorithm check in tpm_pcr_extend() before locks are taken in
tpm_find_get_ops().

Signed-off-by: Roberto Sassu <roberto.sa...@huawei.com>
Fixes: 240730437deb ("KEYS: trusted: explicitly use tpm_chip structure from 
tpm_default_chip()")
---
 drivers/char/tpm/tpm-interface.c | 8 ++++----
 security/keys/trusted.c          | 5 +++++
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 1b4f95c13e00..1fffa91fc148 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -316,14 +316,14 @@ int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
        int rc;
        int i;
 
-       chip = tpm_find_get_ops(chip);
-       if (!chip)
-               return -ENODEV;
-
        for (i = 0; i < chip->nr_allocated_banks; i++)
                if (digests[i].alg_id != chip->allocated_banks[i].alg_id)
                        return -EINVAL;
 
+       chip = tpm_find_get_ops(chip);
+       if (!chip)
+               return -ENODEV;
+
        if (chip->flags & TPM_CHIP_FLAG_TPM2) {
                rc = tpm2_pcr_extend(chip, pcr_idx, digests);
                tpm_put_ops(chip);
diff --git a/security/keys/trusted.c b/security/keys/trusted.c
index ade699131065..1fbd77816610 100644
--- a/security/keys/trusted.c
+++ b/security/keys/trusted.c
@@ -1228,11 +1228,16 @@ static int __init trusted_shash_alloc(void)
 
 static int __init init_digests(void)
 {
+       int i;
+
        digests = kcalloc(chip->nr_allocated_banks, sizeof(*digests),
                          GFP_KERNEL);
        if (!digests)
                return -ENOMEM;
 
+       for (i = 0; i < chip->nr_allocated_banks; i++)
+               digests[i].alg_id = chip->allocated_banks[i].alg_id;
+
        return 0;
 }
 
-- 
2.17.1