The patch below does not apply to the 4.18-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 84b59f6487d82d3ab4247a099aba66d4d17e8b08 Mon Sep 17 00:00:00 2001

From: Jarkko Sakkinen jarkko.sakkinen@linux.intel.com Date: Mon, 3 Sep 2018 04:01:26 +0300 Subject: [PATCH] tpm: fix response size validation in tpm_get_random()

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

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; }