| Message ID | 157601267151.12904.7408818232910113434.stgit@tstruk-mobl1 (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | tpm: fix WARNING: lock held when returning to user space | expand |
On Tue, Dec 10, 2019 at 01:17:51PM -0800, Tadeusz Struk wrote: > When an application sends TPM commands in NONBLOCKING mode > the driver holds chip->tpm_mutex returning from write(), > which triggers WARNING: lock held when returning to user space! > To silence this warning the driver needs to release the mutex > and acquire it again in tpm_dev_async_work() before sending > the command. > > Cc: stable@vger.kernel.org > Fixes: 9e1b74a63f776 (tpm: add support for nonblocking operation) > Signed-off-by: Tadeusz Struk <tadeusz.struk@intel.com> Bundle the patch and test into same patch set (no need for cover letter) in the case we need to iterate (as they must be in sync anyway). /Jarkko
On Tue, Dec 10, 2019 at 01:17:51PM -0800, Tadeusz Struk wrote: > When an application sends TPM commands in NONBLOCKING mode > the driver holds chip->tpm_mutex returning from write(), > which triggers WARNING: lock held when returning to user space! > To silence this warning the driver needs to release the mutex > and acquire it again in tpm_dev_async_work() before sending > the command. This commit message is nonsense ATM. The code leaves locks held, which is unacceptable. Silencing warnings is worst possible rationale for a code change that I can think of starting from the fact that is straight out wrong and malicious. /Jarkko
On Wed, Dec 11, 2019 at 07:52:02PM +0200, Jarkko Sakkinen wrote: > On Tue, Dec 10, 2019 at 01:17:51PM -0800, Tadeusz Struk wrote: > > When an application sends TPM commands in NONBLOCKING mode > > the driver holds chip->tpm_mutex returning from write(), > > which triggers WARNING: lock held when returning to user space! > > To silence this warning the driver needs to release the mutex > > and acquire it again in tpm_dev_async_work() before sending > > the command. > > This commit message is nonsense ATM. The code leaves locks held, > which is unacceptable. > > Silencing warnings is worst possible rationale for a code change > that I can think of starting from the fact that is straight out > wrong and malicious. The code change, however, seems to be doing the right thing. Please bundle it with the test and fix the commit message appropriately. /Jarkko
diff --git a/drivers/char/tpm/tpm-dev-common.c b/drivers/char/tpm/tpm-dev-common.c index 2ec47a69a2a6..b23b0b999232 100644 --- a/drivers/char/tpm/tpm-dev-common.c +++ b/drivers/char/tpm/tpm-dev-common.c @@ -61,6 +61,12 @@ static void tpm_dev_async_work(struct work_struct *work) mutex_lock(&priv->buffer_mutex); priv->command_enqueued = false; + ret = tpm_try_get_ops(priv->chip); + if (ret) { + priv->response_length = ret; + goto out; + } + ret = tpm_dev_transmit(priv->chip, priv->space, priv->data_buffer, sizeof(priv->data_buffer)); tpm_put_ops(priv->chip); @@ -68,6 +74,7 @@ static void tpm_dev_async_work(struct work_struct *work) priv->response_length = ret; mod_timer(&priv->user_read_timer, jiffies + (120 * HZ)); } +out: mutex_unlock(&priv->buffer_mutex); wake_up_interruptible(&priv->async_wait); } @@ -204,6 +211,7 @@ 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; }
When an application sends TPM commands in NONBLOCKING mode the driver holds chip->tpm_mutex returning from write(), which triggers WARNING: lock held when returning to user space! To silence this warning the driver needs to release the mutex and acquire it again in tpm_dev_async_work() before sending the command. Cc: stable@vger.kernel.org Fixes: 9e1b74a63f776 (tpm: add support for nonblocking operation) Signed-off-by: Tadeusz Struk <tadeusz.struk@intel.com> --- drivers/char/tpm/tpm-dev-common.c | 8 ++++++++ 1 file changed, 8 insertions(+)