4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jeremy Boone <jeremy.boone@nccgroup.trust>
commit 6bb320ca4a4a7b5b3db8c8d7250cc40002046878 upstream.
Discrete TPMs are often connected over slow serial buses which, on
some platforms, can have glitches causing bit flips. In all the
driver _recv() functions, we need to use a u32 to unmarshal the
response size, otherwise a bit flip of the 31st bit would cause the
expected variable to go negative, which would then try to read a huge
amount of data. Also sanity check that the expected amount of data is
large enough for the TPM header.
Signed-off-by: Jeremy Boone <jeremy.boone@nccgroup.trust>
Cc: sta...@vger.kernel.org
Signed-off-by: James Bottomley <james.bottom...@hansenpartnership.com>
Tested-by: Jarkko Sakkinen <jarkko.sakki...@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakki...@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakki...@linux.intel.com>
Signed-off-by: James Morris <james.mor...@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
drivers/char/tpm/tpm_tis_core.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -202,7 +202,8 @@ static int tpm_tis_recv(struct tpm_chip
{
struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
int size = 0;
- int expected, status;
+ int status;
+ u32 expected;
if (count < TPM_HEADER_SIZE) {
size = -EIO;
@@ -217,7 +218,7 @@ static int tpm_tis_recv(struct tpm_chip
}
expected = be32_to_cpu(*(__be32 *) (buf + 2));
- if (expected > count) {
+ if (expected > count || expected < TPM_HEADER_SIZE) {
size = -EIO;
goto out;
}
