On Wed, Jan 04, 2017 at 06:47:52PM +0100, Maciej S. Szmigiero wrote:
> (Resending as no reply received, this time with CCs to TPM maintainers and
> author of the original commit).
>
> Hi all,
>
> Commit 1107d065fdf1 (tpm_tis: Introduce intermediate layer for TPM access)
> broke TPM support on ThinkPad X61S (and likely also on other machines which
> use TPMs with a static burst count).
>
> It looks like tpm_tis code before this commit had spun on TPM_STS_DATA_AVAIL |
> TPM_STS_VALID status bits in the read case and TPM_STS_VALID in the write case
> when it got a zero burst count.
>
> I have attached a patch against current code (linux-tpmdd tree) that brings
> back this old behavior.
> With this patch the TPM works again on X61S.
> However, somebody with more TPM experience should comment whether such
> behavior
> was OK or the change brought by commit 1107d065fdf1 was intentional.
>
> Maciej Szmigiero
For me this commit makes perfect sense. Could you do the following things:
1. Clean up the description a little bit
2. Add your Signed-off-by tag.
3. Add "Cc: sta...@vger.kernel.org" tag right after your signed-off-by.
4. CC this linux-security-mod...@vger.kernel.org, sta...@vger.kernel.org,
linux-kernel@vger.kernel.org.
5. Run scripts/checkpatch.pl
6. Re-send for review.
Thanks for fixing the issue. Keep up the good work!
/Jarkko
>
> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> index 7993678954a2..72d365db7c61 100644
> --- a/drivers/char/tpm/tpm_tis_core.c
> +++ b/drivers/char/tpm/tpm_tis_core.c
> @@ -188,7 +188,9 @@ static int recv_data(struct tpm_chip *chip, u8 *buf,
> size_t count)
> if (rc < 0)
> return rc;
> burstcnt = get_burstcount(chip);
> - if (burstcnt < 0) {
> + if (burstcnt == -EBUSY)
> + continue;
> + else if (burstcnt < 0) {
> dev_err(&chip->dev, "Unable to read burstcount\n");
> return burstcnt;
> }
> @@ -282,18 +284,20 @@ static int tpm_tis_send_data(struct tpm_chip *chip, u8
> *buf, size_t len)
>
> while (count < len - 1) {
> burstcnt = get_burstcount(chip);
> - if (burstcnt < 0) {
> + if (burstcnt < 0 && burstcnt != -EBUSY) {
> dev_err(&chip->dev, "Unable to read burstcount\n");
> rc = burstcnt;
> goto out_err;
> + } else if (burstcnt > 0) {
> + burstcnt = min_t(int, burstcnt, len - count - 1);
> + rc = tpm_tis_write_bytes(priv,
> + TPM_DATA_FIFO(priv->locality),
> + burstcnt, buf + count);
> + if (rc < 0)
> + goto out_err;
> +
> + count += burstcnt;
> }
> - burstcnt = min_t(int, burstcnt, len - count - 1);
> - rc = tpm_tis_write_bytes(priv, TPM_DATA_FIFO(priv->locality),
> - burstcnt, buf + count);
> - if (rc < 0)
> - goto out_err;
> -
> - count += burstcnt;
>
> if (wait_for_tpm_stat(chip, TPM_STS_VALID, chip->timeout_c,
> &priv->int_queue, false) < 0) {
