[PATCH v4 1/6] tpm: dynamically allocate active_banks array

[Roberto Sassu]

This patch removes the hard-coded limit of the active_banks array size.
It stores in the tpm_chip structure the number of active PCR banks,
determined in tpm2_get_pcr_allocation(), and replaces the static array
with a pointer to a dynamically allocated array.

As a consequence of the introduction of nr_active_banks, tpm_pcr_extend()
does not check anymore if the algorithm stored in tpm_chip is equal to
zero. The active_banks array always contains valid algorithms.

Fixes: 1db15344f874 ("tpm: implement TPM 2.0 capability to get active
PCR banks")

Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
---
 drivers/char/tpm/tpm-chip.c      |  1 +
 drivers/char/tpm/tpm-interface.c | 19 ++++++++++++-------
 drivers/char/tpm/tpm.h           |  3 ++-
 drivers/char/tpm/tpm2-cmd.c      | 17 ++++++++---------
 4 files changed, 23 insertions(+), 17 deletions(-)

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index 46caadca916a..2a9e8b744436 100644
--- a/drivers/char/tpm/tpm-chip.c
+++ b/drivers/char/tpm/tpm-chip.c
@@ -160,6 +160,7 @@ static void tpm_dev_release(struct device *dev)
 	kfree(chip->log.bios_event_log);
 	kfree(chip->work_space.context_buf);
 	kfree(chip->work_space.session_buf);
+	kfree(chip->active_banks);
 	kfree(chip);
 }
 
diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 1a803b0cf980..ba7ca6b3e664 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -1039,8 +1039,7 @@ static int tpm1_pcr_extend(struct tpm_chip *chip, int pcr_idx, const u8 *hash,
 int tpm_pcr_extend(struct tpm_chip *chip, int pcr_idx, const u8 *hash)
 {
 	int rc;
-	struct tpm2_digest digest_list[ARRAY_SIZE(chip->active_banks)];
-	u32 count = 0;
+	struct tpm2_digest *digest_list;
 	int i;
 
 	chip = tpm_find_get_ops(chip);
@@ -1048,16 +1047,22 @@ int tpm_pcr_extend(struct tpm_chip *chip, int pcr_idx, const u8 *hash)
 		return -ENODEV;
 
 	if (chip->flags & TPM_CHIP_FLAG_TPM2) {
-		memset(digest_list, 0, sizeof(digest_list));
+		digest_list = kmalloc_array(chip->nr_active_banks,
+					    sizeof(*digest_list), GFP_KERNEL);
+		if (!digest_list)
+			return -ENOMEM;
 
-		for (i = 0; i < ARRAY_SIZE(chip->active_banks) &&
-			    chip->active_banks[i] != TPM2_ALG_ERROR; i++) {
+		memset(digest_list, 0,
+		       chip->nr_active_banks * sizeof(*digest_list));
+
+		for (i = 0; i < chip->nr_active_banks; i++) {
 			digest_list[i].alg_id = chip->active_banks[i];
 			memcpy(digest_list[i].digest, hash, TPM_DIGEST_SIZE);
-			count++;
 		}
 
-		rc = tpm2_pcr_extend(chip, pcr_idx, count, digest_list);
+		rc = tpm2_pcr_extend(chip, pcr_idx, chip->nr_active_banks,
+				     digest_list);
+		kfree(digest_list);
 		tpm_put_ops(chip);
 		return rc;
 	}
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index f3501d05264f..98368c3a6ff7 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -248,7 +248,8 @@ struct tpm_chip {
 	const struct attribute_group *groups[3];
 	unsigned int groups_cnt;
 
-	u16 active_banks[7];
+	u32 nr_active_banks;
+	u16 *active_banks;
 #ifdef CONFIG_ACPI
 	acpi_handle acpi_dev_handle;
 	char ppi_version[TPM_PPI_VERSION_LEN + 1];
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index c31b490bd41d..533089cede07 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -242,7 +242,7 @@ int tpm2_pcr_extend(struct tpm_chip *chip, int pcr_idx, u32 count,
 	int i;
 	int j;
 
-	if (count > ARRAY_SIZE(chip->active_banks))
+	if (count > chip->nr_active_banks)
 		return -EINVAL;
 
 	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND);
@@ -859,7 +859,6 @@ static ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
 	void *marker;
 	void *end;
 	void *pcr_select_offset;
-	unsigned int count;
 	u32 sizeof_pcr_selection;
 	u32 rsp_len;
 	int rc;
@@ -878,11 +877,14 @@ static ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
 	if (rc)
 		goto out;
 
-	count = be32_to_cpup(
+	chip->nr_active_banks = be32_to_cpup(
 		(__be32 *)&buf.data[TPM_HEADER_SIZE + 5]);
 
-	if (count > ARRAY_SIZE(chip->active_banks)) {
-		rc = -ENODEV;
+	chip->active_banks = kmalloc_array(chip->nr_active_banks,
+					   sizeof(*chip->active_banks),
+					   GFP_KERNEL);
+	if (!chip->active_banks) {
+		rc = -ENOMEM;
 		goto out;
 	}
 
@@ -891,7 +893,7 @@ static ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
 	rsp_len = be32_to_cpup((__be32 *)&buf.data[2]);
 	end = &buf.data[rsp_len];
 
-	for (i = 0; i < count; i++) {
+	for (i = 0; i < chip->nr_active_banks; i++) {
 		pcr_select_offset = marker +
 			offsetof(struct tpm2_pcr_selection, size_of_select);
 		if (pcr_select_offset >= end) {
@@ -908,9 +910,6 @@ static ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
 	}
 
 out:
-	if (i < ARRAY_SIZE(chip->active_banks))
-		chip->active_banks[i] = TPM2_ALG_ERROR;
-
 	tpm_buf_destroy(&buf);
 
 	return rc;
-- 
2.17.1