From: James Bottomley <james.bottom...@hansenpartnership.com> 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.limoncie...@dell.com> Tested-by: Alex Guzman <a...@guzman.io> Cc: sta...@vger.kernel.org Reviewed-by: Jerry Snitselaar <jsnit...@redhat.com> Signed-off-by: James Bottomley <james.bottom...@hansenpartnership.com> Reviewed-by: Jarkko Sakkinen <jarkko.sakki...@linux.intel.com> Signed-off-by: Jarkko Sakkinen <jarkko.sakki...@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- drivers/char/tpm/tpm-dev-common.c | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-) --- a/drivers/char/tpm/tpm-dev-common.c +++ b/drivers/char/tpm/tpm-dev-common.c @@ -189,15 +189,6 @@ ssize_t tpm_common_write(struct file *fi 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 *fi 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);
