From 8e279e1aecb26cd1816b2495efd1dc16b8a37a02 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()
References: bsc#1082555
Patch-mainline: v4.20-rc1
Git-commit: 84b59f6487d82d3ab4247a099aba66d4d17e8b08
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>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
drivers/char/tpm/tpm-interface.c | 3 ++-
drivers/char/tpm/tpm2-cmd.c | 3 ++-
2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 4c6cd2075270..0318910ade83 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -1283,7 +1283,8 @@ int tpm_get_random(u32 chip_num, 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 6a059d1b124a..620753dcbafe 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -392,7 +392,8 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *out, size_t max)
recd = min_t(u32, be16_to_cpu(cmd.params.getrandom_out.size),
num_bytes);
rlength = be32_to_cpu(cmd.header.out.length);
- if (rlength < offsetof(struct tpm2_get_random_out, buffer) +
+ if (rlength < TPM_HEADER_SIZE +
+ offsetof(struct tpm2_get_random_out, buffer) +
recd)
return -EFAULT;
memcpy(dest, cmd.params.getrandom_out.buffer, recd);
--
2.13.7