Ubuntu
linux package

  1. Focal (20.04)
  2. Bug #1881710
  3. Comment #0

Comment 0 for bug 1881710

Revision history for this message
Ivan Hu (ivan.hu) wrote :

Link: https://patchwork.kernel.org/patch/11576453/

[Impact]
   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. This affects Nuvoton TPMs and was a regression caused by the patch d23d12484307 ("tpm: fix invalid locking in NONBLOCKING mode").
Link: https://patchwork.kernel.org/patch/11576453/

[Fix]
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.

[Regression Risk]
Low. This patch only for fix the patch d23d12484307 ("tpm: fix invalid locking in NONBLOCKING mode").