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Subject[PATCH v3] KEYS: trusted: correctly initialize digests and fix locking issue
Date
Commit 0b6cf6b97b7e ("tpm: pass an array of tpm_extend_digest structures to
tpm_pcr_extend()") modifies tpm_pcr_extend() to accept a digest for each
PCR bank. After modification, tpm_pcr_extend() expects that digests are
passed in the same order as the algorithms set in chip->allocated_banks.

This patch fixes two issues introduced in the last iterations of the patch
set: missing initialization of the TPM algorithm ID in the tpm_digest
structures passed to tpm_pcr_extend() by the trusted key module, and
unreleased locks in the TPM driver due to returning from tpm_pcr_extend()
without calling tpm_put_ops(). To avoid the second issue, input check is
done before locks are taken.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Fixes: 0b6cf6b97b7e ("tpm: pass an array of tpm_extend_digest structures to tpm_pcr_extend()")
---
Changelog

v2:
- provide explanation of the problem

v1:
- correct referenced commit

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
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