--- /dev/null
+From faf07e611dfa464b201223a7253e9dc5ee0f3c9e Mon Sep 17 00:00:00 2001
+From: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>
+Date: Tue, 30 Sep 2025 15:58:02 +0300
+Subject: tpm: Cap the number of PCR banks
+
+From: Jarkko Sakkinen <jarkko.sakkinen@opinsys.com>
+
+commit faf07e611dfa464b201223a7253e9dc5ee0f3c9e upstream.
+
+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>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ drivers/char/tpm/tpm-chip.c | 1 -
+ drivers/char/tpm/tpm1-cmd.c | 5 -----
+ drivers/char/tpm/tpm2-cmd.c | 8 +++-----
+ include/linux/tpm.h | 8 +++++---
+ 4 files changed, 8 insertions(+), 14 deletions(-)
+
+--- a/drivers/char/tpm/tpm-chip.c
++++ b/drivers/char/tpm/tpm-chip.c
+@@ -269,7 +269,6 @@ static void tpm_dev_release(struct devic
+
+ kfree(chip->work_space.context_buf);
+ kfree(chip->work_space.session_buf);
+- kfree(chip->allocated_banks);
+ kfree(chip);
+ }
+
+--- a/drivers/char/tpm/tpm1-cmd.c
++++ b/drivers/char/tpm/tpm1-cmd.c
+@@ -794,11 +794,6 @@ int tpm1_pm_suspend(struct tpm_chip *chi
+ */
+ 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;
+--- a/drivers/char/tpm/tpm2-cmd.c
++++ b/drivers/char/tpm/tpm2-cmd.c
+@@ -574,11 +574,9 @@ ssize_t tpm2_get_pcr_allocation(struct t
+
+ 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;
+ }
+--- a/include/linux/tpm.h
++++ b/include/linux/tpm.h
+@@ -25,7 +25,9 @@
+ #include <crypto/hash_info.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;
+@@ -44,7 +46,7 @@ enum tpm_algorithms {
+
+ struct tpm_digest {
+ u16 alg_id;
+- u8 digest[TPM_MAX_DIGEST_SIZE];
++ u8 digest[TPM2_MAX_DIGEST_SIZE];
+ } __packed;
+
+ struct tpm_bank_info {
+@@ -150,7 +152,7 @@ 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];