On Thu, Oct 20, 2016 at 05:21:29PM -0700, Josh Zimmerman wrote:
> If the TPM we're connecting to uses a static burst count, it will report
> a burst count of zero throughout the response read. However, get_burstcount
> assumes that a response of zero indicates that the TPM is not ready to
> receive more data. In this case, it returns a negative error code, which
> is passed on to tpm_tis_{write,read}_bytes as a u16, causing
> them to read/write far too many bytes.
>
> This patch checks for negative return codes and bails out from recv_data
> and tpm_tis_send_data.
I guess this would need a "Fixes:" tag, wouldn't it? I would also add
Cc: [email protected]
> ---
> drivers/char/tpm/tpm_tis_core.c | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> index e3bf31b..d0301dc 100644
> --- a/drivers/char/tpm/tpm_tis_core.c
> +++ b/drivers/char/tpm/tpm_tis_core.c
> @@ -186,6 +186,12 @@ static int recv_data(struct tpm_chip *chip, u8 *buf,
> size_t count)
> chip->timeout_c,
> &priv->read_queue, true) == 0) {
> burstcnt = min_t(int, get_burstcount(chip), count - size);
> + if (burstcnt < 0) {
> + dev_err(&chip->dev,
> + "Unable to read burstcount in %s:%d (%s)\n",
> + __FILE__, __LINE__, __func__);
> + return rc;
> + }
"return burstcnt;"
I guess __func__ would be enough to deduce the call site?
> rc = tpm_tis_read_bytes(priv, TPM_DATA_FIFO(priv->locality),
> burstcnt, buf + size);
> @@ -272,6 +278,13 @@ static int tpm_tis_send_data(struct tpm_chip *chip, u8
> *buf, size_t len)
>
> while (count < len - 1) {
> burstcnt = min_t(int, get_burstcount(chip), len - count - 1);
> + if (burstcnt < 0) {
> + dev_err(&chip->dev,
> + "Unable to read burstcount in %s:%d (%s)\n",
> + __FILE__, __LINE__, __func__);
> + rc = burstcnt;
> + goto out_err;
> + }
> rc = tpm_tis_write_bytes(priv, TPM_DATA_FIFO(priv->locality),
> burstcnt, buf + count);
> if (rc < 0)
> --
> 2.8.0.rc3.226.g39d4020
/Jarkko
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