Re: [PATCH v2] tpm: prevents local DOS via tpm/tpm0/ppi/*operations

[Jarkko Sakkinen <jarkko@kernel.org>]

On Tue, Aug 26, 2025 at 10:21:02PM -0400, Denis Aleksandrov wrote:
> Reads on tpm/tpm0/ppi/*operations can become very long on
> misconfigured systems. Reading the TPM is a blocking operation,
> thus a user could effectively trigger a DOS.
> 
> Resolve this by caching the results and avoiding the blocking
> operations after the first read.
> 
> Reported-by: Jan Stancek <jstancek@redhat.com>
> Signed-off-by: Denis Aleksandrov <daleksan@redhat.com>

I can already say that this definitely to the right direction.  Thanks
for taking time revisiting this, and taking time to restructure it.

I'll give more detailed review later on. One nitpick:

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

You put this whenever the proposal for "final solution" comes from
an outside source. It's a good practice, and it's not only for the
credit, but also to get to the blame if my proposal turns out to
be an epic failure ;-)

But yeah, hold on for detailed review.

BR, Jarkko