The patch below does not apply to the 4.4-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@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 6bb320ca4a4a7b5b3db8c8d7250cc40002046878 Mon Sep 17 00:00:00 2001
From: Jeremy Boone <jeremy.boone@nccgroup.trust>
Date: Thu, 8 Feb 2018 12:32:06 -0800
Subject: [PATCH] tpm_tis: fix potential buffer overruns caused by bit glitches
on the bus
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: stable@xxxxxxxxxxxxxxx
Signed-off-by: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
Signed-off-by: James Morris <james.morris@xxxxxxxxxxxxx>
diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 183a5f54d875..da074e3db19b 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -270,7 +270,8 @@ static int tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count)
{
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;
@@ -285,7 +286,7 @@ static int tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count)
}
expected = be32_to_cpu(*(__be32 *) (buf + 2));
- if (expected > count) {
+ if (expected > count || expected < TPM_HEADER_SIZE) {
size = -EIO;
goto out;
}