On 09/02/2018 09:10 PM, Jarkko Sakkinen wrote:

When checking whether the response is large enough to be able to contain the received random bytes in tpm_get_random() and tpm2_get_random(), they fail to take account the header size, which should be added to the minimum size. This commit fixes this issue.

Cc: stable@vger.kernel.org Fixes: c659af78eb7b ("tpm: Check size of response before accessing data") Signed-off-by: Jarkko Sakkinen jarkko.sakkinen@linux.intel.com

---

drivers/char/tpm/tpm-interface.c | 3 ++- drivers/char/tpm/tpm2-cmd.c | 4 +++- 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c index 1a803b0cf980..318a7078b2ba 100644 --- a/drivers/char/tpm/tpm-interface.c +++ b/drivers/char/tpm/tpm-interface.c @@ -1321,7 +1321,8 @@ int tpm_get_random(struct tpm_chip *chip, u8 *out, size_t max) }

rlength = be32_to_cpu(tpm_cmd.header.out.length);

• if (rlength < offsetof(struct tpm_getrandom_out, rng_data) +
  

• if (rlength < TPM_HEADER_SIZE +
  

• 	      offsetof(struct tpm_getrandom_out, rng_data) +
        recd) {
  total = -EFAULT;
  break;
  

diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c index c31b490bd41d..3acf4fd4e5a5 100644 --- a/drivers/char/tpm/tpm2-cmd.c +++ b/drivers/char/tpm/tpm2-cmd.c @@ -329,7 +329,9 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max) &buf.data[TPM_HEADER_SIZE]; recd = min_t(u32, be16_to_cpu(out->size), num_bytes); if (tpm_buf_length(&buf) <

•     offsetof(struct tpm2_get_random_out, buffer) + recd) {
  

•     TPM_HEADER_SIZE +
  

•     offsetof(struct tpm2_get_random_out, buffer) +
  

•     recd) {
  err = -EFAULT;
  goto out;
  

  }

Reviewed-by: Stefan Berger stefanb@linux.vnet.ibm.com