Messages in this thread | | | Date | Mon, 29 Aug 2016 18:25:21 +0300 | From | Jarkko Sakkinen <> | Subject | Re: [PATCH] tpm: fix a race condition in tpm2_unseal_trusted() |
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On Sun, Aug 28, 2016 at 12:51:49PM -0600, Jason Gunthorpe wrote: > On Sun, Aug 28, 2016 at 08:36:52AM +0200, Jarkko Sakkinen wrote: > > > > @@ -576,7 +576,8 @@ static int tpm2_load(struct tpm_chip *chip, > > goto out; > > } > > > > - rc = tpm_transmit_cmd(chip, buf.data, PAGE_SIZE, "loading blob"); > > + rc = tpm_transmit_cmd(chip, buf.data, PAGE_SIZE, TPM_TRANSMIT_UNLOCKED, > > + "loading blob"); > > I still don't like this, required mutex's should not be split outside the > function that needs them without more a more obvious indication: > > > + mutex_lock(&chip->tpm_mutex); > > rc = tpm2_load(chip, payload, options, &blob_handle); > > if (rc) > > - return rc; > > I recommend you stick with the idiom and do this: > > mutex_lock(&chip->tpm_mutex); > rc = tpm2_load(chip, payload, options, &blob_handle, TPM_TRANSMIT_UNLOCKED); > > Which makes it easy to see we are doing it right everywhere.
Why consume stack for unnecessary stuff? This is a static function. For me this sounds like cutting hairs really.
One thing that would improve readability would be to rename internal functions tpm2_load and tpm2_unseal to tpm2_load_cmd and tpm2_unseal_cmd in order to underline that they are command wrappers and not to mix with tpm2_unseal_trusted().
I've been thinking to move that kind of convetion at least with TPM2 specific stuff when a function is clearly a wrapper. It kind of documents the call path. I.e. if function satifies a constraint that it prepares a command blob, calls tpm_transmit_cmd once and then returns results to the caller this would be the naming convention.
> Jason
/Jarkko
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