Patch "tpm_tis_core: Choose appropriate timeout for reading burstcount" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

tpm_tis_core: Choose appropriate timeout for reading burstcount

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
tpm_tis_core-choose-appropriate-timeout-for-reading-burstcount.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Alexander Steffen <[email protected]>
Date: Thu, 16 Feb 2017 15:33:36 +0000
Subject: tpm_tis_core: Choose appropriate timeout for reading burstcount

From: Alexander Steffen <[email protected]>

commit 302a6ad7fc77146191126a1f3e2c5d724fd72416 upstream.

TIS v1.3 for TPM 1.2 and PTP for TPM 2.0 disagree about which timeout value applies to reading a valid burstcount. It is TIMEOUT_D according to TIS, but TIMEOUT_A according to PTP, so choose the appropriate value depending on whether we deal with a TPM 1.2 or a TPM 2.0.

This is important since according to the PTP TIMEOUT_D is much smaller than TIMEOUT_A. So the previous implementation could run into timeouts with a TPM 2.0, even though the TPM was behaving perfectly fine.

During tpm2_probe TIMEOUT_D will be used even with a TPM 2.0, because TPM_CHIP_FLAG_TPM2 is not yet set. This is fine, since the timeout values will only be changed afterwards by tpm_get_timeouts. Until then TIS_TIMEOUT_D_MAX applies, which is large enough.

---
 drivers/char/tpm/tpm_tis_core.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

@@ -160,8 +160,10 @@ static int get_burstcount(struct tpm_chi
 	u32 value;
 
 	/* wait for burstcount */
-	/* which timeout value, spec has 2 answers (c & d) */
-	stop = jiffies + chip->timeout_d;
+	if (chip->flags & TPM_CHIP_FLAG_TPM2)
+		stop = jiffies + chip->timeout_a;
+	else
+		stop = jiffies + chip->timeout_d;
 	do {
 		rc = tpm_tis_read32(priv, TPM_STS(priv->locality), &value);
 		if (rc < 0)

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/tpm_tis_core-choose-appropriate-timeout-for-reading-burstcount.patch