Commit 78628402 authored by James Bottomley's avatar James Bottomley Committed by Jarkko Sakkinen
Browse files

tpm: Fix TIS locality timeout problems 

It has been reported that some TIS based TPMs are giving unexpected
errors when using the O_NONBLOCK path of the TPM device. The problem
is that some TPMs don't like it when you get and then relinquish a
locality (as the tpm_try_get_ops()/tpm_put_ops() pair does) without
sending a command.  This currently happens all the time in the
O_NONBLOCK write path. Fix this by moving the tpm_try_get_ops()
further down the code to after the O_NONBLOCK determination is made.
This is safe because the priv->buffer_mutex still protects the priv
state being modified.

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=206275


Fixes: d23d1248 ("tpm: fix invalid locking in NONBLOCKING mode")
Reported-by: default avatarMario Limonciello <Mario.Limonciello@dell.com>
Tested-by: default avatarAlex Guzman <alex@guzman.io>
Cc: stable@vger.kernel.org
Reviewed-by: default avatarJerry Snitselaar <jsnitsel@redhat.com>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
Reviewed-by: default avatarJarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: default avatarJarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
parent cd77006e

drivers/char/tpm/tpm-dev-common.c

+9 −10
Original line number Diff line number Diff line
@@ -189,15 +189,6 @@ ssize_t tpm_common_write(struct file *file, const char __user *buf, 
		goto out;

	}



	/* atomic tpm command send and result receive. We only hold the ops

	 * lock during this period so that the tpm can be unregistered even if

	 * the char dev is held open.

	 */

	if (tpm_try_get_ops(priv->chip)) {

		ret = -EPIPE;

		goto out;

	}



	priv->response_length = 0;

	priv->response_read = false;

	*off = 0;
@@ -211,11 +202,19 @@ ssize_t tpm_common_write(struct file *file, const char __user *buf, 
	if (file->f_flags & O_NONBLOCK) {

		priv->command_enqueued = true;

		queue_work(tpm_dev_wq, &priv->async_work);

		tpm_put_ops(priv->chip);

		mutex_unlock(&priv->buffer_mutex);

		return size;

	}



	/* atomic tpm command send and result receive. We only hold the ops

	 * lock during this period so that the tpm can be unregistered even if

	 * the char dev is held open.

	 */

	if (tpm_try_get_ops(priv->chip)) {

		ret = -EPIPE;

		goto out;

	}



	ret = tpm_dev_transmit(priv->chip, priv->space, priv->data_buffer,

			       sizeof(priv->data_buffer));

	tpm_put_ops(priv->chip);