Patch "tpm_crb: fix crb_req_canceled behavior" has been added to the 4.8-stable tree

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

tpm_crb: fix crb_req_canceled behavior

to the 4.8-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_crb-fix-crb_req_canceled-behavior.patch
and it can be found in the queue-4.8 subdirectory.

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

From: Jarkko Sakkinen <[email protected]>
Date: Fri, 2 Sep 2016 22:34:17 +0300
Subject: tpm_crb: fix crb_req_canceled behavior

From: Jarkko Sakkinen <[email protected]>

commit 72fd50e14e46dc0edf360631bdece87c2f066a97 upstream.

The req_canceled() callback is used by tpm_transmit() periodically to check whether the request has been canceled while it is receiving a response from the TPM.

The TPM_CRB_CTRL_CANCEL register was cleared already in the crb_cancel callback, which has two consequences:

* Cancel might not happen.
* req_canceled() always returns zero.

A better place to clear the register is when starting to send a new command. The behavior of TPM_CRB_CTRL_CANCEL is described in the section 5.5.3.6 of the PTP specification.

---
 drivers/char/tpm/tpm_crb.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

@@ -142,6 +142,11 @@ static int crb_send(struct tpm_chip *chi
 	struct crb_priv *priv = dev_get_drvdata(&chip->dev);
 	int rc = 0;
 
+	/* Zero the cancel register so that the next command will not get
+	 * canceled.
+	 */
+	iowrite32(0, &priv->cca->cancel);
+
 	if (len > ioread32(&priv->cca->cmd_size)) {
 		dev_err(&chip->dev,
 			"invalid command count value %x %zx\n",

@@ -175,8 +180,6 @@ static void crb_cancel(struct tpm_chip *
 
 	if ((priv->flags & CRB_FL_ACPI_START) && crb_do_acpi_start(chip))
 		dev_err(&chip->dev, "ACPI Start failed\n");
-
-	iowrite32(0, &priv->cca->cancel);
 }
 
 static bool crb_req_canceled(struct tpm_chip *chip, u8 status)

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

queue-4.8/tpm_crb-fix-crb_req_canceled-behavior.patch queue-4.8/tpm-fix-a-race-condition-in-tpm2_unseal_trusted.patch