This patch ensures that the digest size returned by the TPM during a PCR read matches the size of the algorithm passed as argument to tpm2_pcr_read(). The check is performed after information about the PCR banks has been retrieved. Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx> --- drivers/char/tpm/tpm2-cmd.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c index 8e821e7b4674..477dcc30fc53 100644 --- a/drivers/char/tpm/tpm2-cmd.c +++ b/drivers/char/tpm/tpm2-cmd.c @@ -187,15 +187,28 @@ struct tpm2_pcr_read_out { int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx, struct tpm_digest *digest_struct, u16 *digest_size_ptr) { + int i; int rc; struct tpm_buf buf; struct tpm2_pcr_read_out *out; u8 pcr_select[TPM2_PCR_SELECT_MIN] = {0}; u16 digest_size; + u16 expected_digest_size = 0; if (pcr_idx >= TPM2_PLATFORM_PCR) return -EINVAL; + if (!digest_size_ptr) { + for (i = 0; i < ARRAY_SIZE(chip->active_banks) && + chip->active_banks[i].alg_id != digest_struct->alg_id; i++) + ; + + if (i == ARRAY_SIZE(chip->active_banks)) + return -EINVAL; + + expected_digest_size = chip->active_banks[i].digest_size; + } + rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_PCR_READ); if (rc) return rc; @@ -215,7 +228,8 @@ int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx, out = (struct tpm2_pcr_read_out *)&buf.data[TPM_HEADER_SIZE]; digest_size = be16_to_cpu(out->digest_size); - if (digest_size > sizeof(digest_struct->digest)) { + if ((digest_size_ptr && digest_size > sizeof(digest_struct->digest)) || + (!digest_size_ptr && digest_size != expected_digest_size)) { rc = -EINVAL; goto out; } -- 2.17.1