Commit 5d6b46a9 authored May 28, 2020 by James Bottomley Committed by Greg Kroah-Hartman Jul 09, 2020

tpm: Fix TIS locality timeout problems

commit 7862840219058436b80029a0263fd1ef065fb1b3 upstream.

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: d23d12484307 ("tpm: fix invalid locking in NONBLOCKING mode")
Reported-by: Mario Limonciello <Mario.Limonciello@dell.com>
Tested-by: Alex Guzman <alex@guzman.io>
Cc: stable@vger.kernel.org
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 563e9491

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);