tpm: Cap the number of PCR banks

tpm2_get_pcr_allocation() does not cap any upper limit for the number of
banks. Cap the limit to eight banks so that out of bounds values coming
from external I/O cause on only limited harm.

Cc: stable@vger.kernel.org # v5.10+
Fixes: bcfff8384f6c ("tpm: dynamically allocate the allocated_banks array")
Tested-by: Lai Yi <yi1.lai@linux.intel.com>
Reviewed-by: Jonathan McDowell <noodles@meta.com>
Reviewed-by: Roberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index 30d00219f9f3cf9e30ab6eb1b4027555b2d65a67..082b910ddf0dd8bb894c7beec5e1f27aaa8c87b9 100644 (file)
--- a/drivers/char/tpm/tpm-chip.c
+++ b/drivers/char/tpm/tpm-chip.c
@@ -246,7 +246,6 @@ static void tpm_dev_release(struct device *dev)
 
        kfree(chip->work_space.context_buf);
        kfree(chip->work_space.session_buf);
-       kfree(chip->allocated_banks);
 #ifdef CONFIG_TCG_TPM2_HMAC
        kfree(chip->auth);
 #endif

diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c
index cf64c738510529bc8b8a751bdaac20cfe6b884bc..b49a790f1bd53fac29a3d70a87d4f1d3ad9cf869 100644 (file)
--- a/drivers/char/tpm/tpm1-cmd.c
+++ b/drivers/char/tpm/tpm1-cmd.c
@@ -799,11 +799,6 @@ int tpm1_pm_suspend(struct tpm_chip *chip, u32 tpm_suspend_pcr)
  */
 int tpm1_get_pcr_allocation(struct tpm_chip *chip)
 {
-       chip->allocated_banks = kcalloc(1, sizeof(*chip->allocated_banks),
-                                       GFP_KERNEL);
-       if (!chip->allocated_banks)
-               return -ENOMEM;
-
        chip->allocated_banks[0].alg_id = TPM_ALG_SHA1;
        chip->allocated_banks[0].digest_size = hash_digest_size[HASH_ALGO_SHA1];
        chip->allocated_banks[0].crypto_id = HASH_ALGO_SHA1;

diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 5532e53a2dd3da6b39f81ac3a63dc782aad55929..dd502322f4998b02caf66abb580c99b451461f41 100644 (file)
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -550,11 +550,9 @@ ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
 
        nr_possible_banks = be32_to_cpup(
                (__be32 *)&buf.data[TPM_HEADER_SIZE + 5]);
-
-       chip->allocated_banks = kcalloc(nr_possible_banks,
-                                       sizeof(*chip->allocated_banks),
-                                       GFP_KERNEL);
-       if (!chip->allocated_banks) {
+       if (nr_possible_banks > TPM2_MAX_PCR_BANKS) {
+               pr_err("tpm: out of bank capacity: %u > %u\n",
+                      nr_possible_banks, TPM2_MAX_PCR_BANKS);
                rc = -ENOMEM;
                goto out;
        }

diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index b15360ff78d7640198c5248cd7ba8b2c537a6f0f..53de9488c509ec64de45bb29b9a4c8a5dcad22ae 100644 (file)
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -26,7 +26,9 @@
 #include <crypto/aes.h>
 
 #define TPM_DIGEST_SIZE 20     /* Max TPM v1.2 PCR size */
-#define TPM_MAX_DIGEST_SIZE SHA512_DIGEST_SIZE
+
+#define TPM2_MAX_DIGEST_SIZE   SHA512_DIGEST_SIZE
+#define TPM2_MAX_PCR_BANKS     8
 
 struct tpm_chip;
 struct trusted_key_payload;
@@ -68,7 +70,7 @@ enum tpm2_curves {
 
 struct tpm_digest {
        u16 alg_id;
-       u8 digest[TPM_MAX_DIGEST_SIZE];
+       u8 digest[TPM2_MAX_DIGEST_SIZE];
 } __packed;
 
 struct tpm_bank_info {
@@ -189,7 +191,7 @@ struct tpm_chip {
        unsigned int groups_cnt;
 
        u32 nr_allocated_banks;
-       struct tpm_bank_info *allocated_banks;
+       struct tpm_bank_info allocated_banks[TPM2_MAX_PCR_BANKS];
 #ifdef CONFIG_ACPI
        acpi_handle acpi_dev_handle;
        char ppi_version[TPM_PPI_VERSION_LEN + 1];