[PATCH 4.19 268/361] tpm: fix response size validation in tpm_get_random()

Greg Kroah-Hartman
2018-11-11T23:55:19Z

From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

commit 84b59f6487d82d3ab4247a099aba66d4d17e8b08 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -1322,7 +1322,8 @@ int tpm_get_random(struct tpm_chip *chip
}

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;
--- 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 *chi
&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;
}