diff mbox series

[v4,1/2] tpm: Fix error handling in async work

Message ID 20220116012627.2031-1-tstruk@gmail.com (mailing list archive)
State New
Headers show
Series [v4,1/2] tpm: Fix error handling in async work | expand

Commit Message

Tadeusz Struk Jan. 16, 2022, 1:26 a.m. UTC
When an invalid (non existing) handle is used in a TPM command,
that uses the resource manager interface (/dev/tpmrm0) the resource
manager tries to load it from its internal cache, but fails and
the tpm_dev_transmit returns an -EINVAL error to the caller.
The existing async handler doesn't handle these error cases
currently and the condition in the poll handler never returns
mask with EPOLLIN set.
The result is that the poll call blocks and the application gets stuck
until the user_read_timer wakes it up after 120 sec.
Change the tpm_dev_async_work function to handle error conditions
returned from tpm_dev_transmit they are also reflected in the poll mask
and a correct error code could passed back to the caller.

Cc: Jarkko Sakkinen <jarkko@kernel.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: <linux-integrity@vger.kernel.org>
Cc: <stable@vger.kernel.org>
Cc: <linux-kernel@vger.kernel.org>

Fixes: 9e1b74a63f77 ("tpm: add support for nonblocking operation")
Tested-by: Jarkko Sakkinen<jarkko@kernel.org>
Signed-off-by: Tadeusz Struk <tstruk@gmail.com>
---
Changed in v2:
- Updated commit message with better problem description
- Fixed typeos.
Changed in v3:
- Added a comment to tpm_dev_async_work.
- Updated commit message.
Changed in v4:
- Fixed a typo in the comment.
---
 drivers/char/tpm/tpm-dev-common.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

Comments

Jarkko Sakkinen Jan. 16, 2022, 2:34 p.m. UTC | #1
On Sat, Jan 15, 2022 at 05:26:26PM -0800, Tadeusz Struk wrote:
> When an invalid (non existing) handle is used in a TPM command,
> that uses the resource manager interface (/dev/tpmrm0) the resource
> manager tries to load it from its internal cache, but fails and
> the tpm_dev_transmit returns an -EINVAL error to the caller.
> The existing async handler doesn't handle these error cases
> currently and the condition in the poll handler never returns
> mask with EPOLLIN set.
> The result is that the poll call blocks and the application gets stuck
> until the user_read_timer wakes it up after 120 sec.
> Change the tpm_dev_async_work function to handle error conditions
> returned from tpm_dev_transmit they are also reflected in the poll mask
> and a correct error code could passed back to the caller.
> 
> Cc: Jarkko Sakkinen <jarkko@kernel.org>
> Cc: Jason Gunthorpe <jgg@ziepe.ca>
> Cc: <linux-integrity@vger.kernel.org>
> Cc: <stable@vger.kernel.org>
> Cc: <linux-kernel@vger.kernel.org>
> 
> Fixes: 9e1b74a63f77 ("tpm: add support for nonblocking operation")
> Tested-by: Jarkko Sakkinen<jarkko@kernel.org>
> Signed-off-by: Tadeusz Struk <tstruk@gmail.com>

Thank you.

Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>

BR, Jarkko
diff mbox series

Patch

diff --git a/drivers/char/tpm/tpm-dev-common.c b/drivers/char/tpm/tpm-dev-common.c
index c08cbb306636..dc4c0a0a5129 100644
--- a/drivers/char/tpm/tpm-dev-common.c
+++ b/drivers/char/tpm/tpm-dev-common.c
@@ -69,7 +69,13 @@  static void tpm_dev_async_work(struct work_struct *work)
 	ret = tpm_dev_transmit(priv->chip, priv->space, priv->data_buffer,
 			       sizeof(priv->data_buffer));
 	tpm_put_ops(priv->chip);
-	if (ret > 0) {
+
+	/*
+	 * If ret is > 0 then tpm_dev_transmit returned the size of the
+	 * response. If ret is < 0 then tpm_dev_transmit failed and
+	 * returned an error code.
+	 */
+	if (ret != 0) {
 		priv->response_length = ret;
 		mod_timer(&priv->user_read_timer, jiffies + (120 * HZ));
 	}