On Fri, Feb 02, 2018 at 06:25:33PM +0100, James Bottomley wrote:
> From: Jeremy Boone <jeremy.boone@nccgroup.trust>
>
> 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>
> ---
> drivers/char/tpm/st33zp24/st33zp24.c | 4 ++--
> drivers/char/tpm/tpm_i2c_infineon.c | 5 +++--
> drivers/char/tpm/tpm_i2c_nuvoton.c | 5 +++--
> drivers/char/tpm/tpm_tis_core.c | 5 +++--
> 4 files changed, 11 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/char/tpm/st33zp24/st33zp24.c b/drivers/char/tpm/st33zp24/st33zp24.c
> index 4d1dc8b46877..f95b9c75175b 100644
> --- a/drivers/char/tpm/st33zp24/st33zp24.c
> +++ b/drivers/char/tpm/st33zp24/st33zp24.c
> @@ -457,7 +457,7 @@ static int st33zp24_recv(struct tpm_chip *chip, unsigned char *buf,
> size_t count)
> {
> int size = 0;
> - int expected;
> + u32 expected;
>
> if (!chip)
> return -EBUSY;
> @@ -474,7 +474,7 @@ static int st33zp24_recv(struct tpm_chip *chip, unsigned char *buf,
> }
>
> expected = be32_to_cpu(*(__be32 *)(buf + 2));
> - if (expected > count) {
> + if (expected > count || expected < TPM_HEADER_SIZE) {
> size = -EIO;
> goto out;
> }
> diff --git a/drivers/char/tpm/tpm_i2c_infineon.c b/drivers/char/tpm/tpm_i2c_infineon.c
> index 79d6bbb58e39..d5b44cadac56 100644
> --- a/drivers/char/tpm/tpm_i2c_infineon.c
> +++ b/drivers/char/tpm/tpm_i2c_infineon.c
> @@ -473,7 +473,8 @@ static int recv_data(struct tpm_chip *chip, u8 *buf, size_t count)
> static int tpm_tis_i2c_recv(struct tpm_chip *chip, u8 *buf, size_t count)
> {
> int size = 0;
> - int expected, status;
> + int status;
> + u32 expected;
>
> if (count < TPM_HEADER_SIZE) {
> size = -EIO;
> @@ -488,7 +489,7 @@ static int tpm_tis_i2c_recv(struct tpm_chip *chip, u8 *buf, size_t count)
> }
>
> expected = be32_to_cpu(*(__be32 *)(buf + 2));
> - if ((size_t) expected > count) {
> + if (((size_t) expected > count) || (expected < TPM_HEADER_SIZE)) {
> size = -EIO;
> goto out;
> }
> diff --git a/drivers/char/tpm/tpm_i2c_nuvoton.c b/drivers/char/tpm/tpm_i2c_nuvoton.c
> index c6428771841f..17cf7af9a2c5 100644
> --- a/drivers/char/tpm/tpm_i2c_nuvoton.c
> +++ b/drivers/char/tpm/tpm_i2c_nuvoton.c
> @@ -281,7 +281,8 @@ static int i2c_nuvoton_recv(struct tpm_chip *chip, u8 *buf, size_t count)
> struct device *dev = chip->dev.parent;
> struct i2c_client *client = to_i2c_client(dev);
> s32 rc;
> - int expected, status, burst_count, retries, size = 0;
> + int status, burst_count, retries, size = 0;
> + u32 expected;
>
> if (count < TPM_HEADER_SIZE) {
> i2c_nuvoton_ready(chip); /* return to idle */
> @@ -323,7 +324,7 @@ static int i2c_nuvoton_recv(struct tpm_chip *chip, u8 *buf, size_t count)
> * to machine native
> */
> expected = be32_to_cpu(*(__be32 *) (buf + 2));
> - if (expected > count) {
> + if (expected > count || expected < size) {
> dev_err(dev, "%s() expected > count\n", __func__);
> size = -EIO;
> continue;
> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> index fdde971bc810..7561922bc8f8 100644
> --- 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 *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;
> @@ -217,7 +218,7 @@ 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;
> }
> --
> 2.12.3
LGTM but should be split into four commits.
/Jarkko
