linux-kernel - Re: [PATCH 1/3] tpm: Add a missing check for TPM_CHIP_FLAG_HWRNG

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Date:   Sat, 05 Aug 2023 01:52:17 +0300
From:   "Jarkko Sakkinen" <jarkko@...nel.org>
To:     "Jason A. Donenfeld" <Jason@...c4.com>,
        "Mario Limonciello" <mario.limonciello@....com>
Cc:     <peterhuewe@....de>, <linux-kernel@...r.kernel.org>,
        <linux-integrity@...r.kernel.org>, <dragonn@...pl>
Subject: Re: [PATCH 1/3] tpm: Add a missing check for
 TPM_CHIP_FLAG_HWRNG_DISABLED

On Thu Aug 3, 2023 at 4:50 PM EEST, Jason A. Donenfeld wrote:
> On Thu, Aug 03, 2023 at 06:35:36AM -0500, Mario Limonciello wrote:
> > On 8/3/23 03:59, Jarkko Sakkinen wrote:
> > > On Thu Aug 3, 2023 at 4:50 AM EEST, Mario Limonciello wrote:
> > >> If the TPM is opted out of hwrng the error handling for
> > >> tpm_chip_register() needs to know this so it doesn't try to clean
> > >> up an uninitialized chip->hwrng.
> > >>
> > >> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
> > >> ---
> > >>   drivers/char/tpm/tpm-chip.c | 3 ++-
> > >>   1 file changed, 2 insertions(+), 1 deletion(-)
> > >>
> > >> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> > >> index e904aae9771be..8f61b784810d6 100644
> > >> --- a/drivers/char/tpm/tpm-chip.c
> > >> +++ b/drivers/char/tpm/tpm-chip.c
> > >> @@ -629,7 +629,8 @@ int tpm_chip_register(struct tpm_chip *chip)
> > >>   	return 0;
> > >>   
> > >>   out_hwrng:
> > >> -	if (IS_ENABLED(CONFIG_HW_RANDOM_TPM) && !tpm_is_firmware_upgrade(chip))
> > >> +	if (IS_ENABLED(CONFIG_HW_RANDOM_TPM) && !tpm_is_firmware_upgrade(chip) &&
> > >> +	    !(chip->flags & TPM_CHIP_FLAG_HWRNG_DISABLED))
> > >>   		hwrng_unregister(&chip->hwrng);
> > >>   out_ppi:
> > >>   	tpm_bios_log_teardown(chip);
> > >> -- 
> > >> 2.34.1
> > > 
> > > Please add a fixes tag.
> > > 
> > > BR, Jarkko
> > 
> > I didn't add a fixes tag because you hadn't sent a PR for the other one 
> > yet so I wasn't sure the hash would be stable.  Also I thought it might 
> > just make sense to squash into it.
> > 
> > If the hash is now stable, could you just just commit and add that tag 
> > with it yourself?  Or do you want me to re-send as a v2 with that?
>
> What about just sending a v3 of the patch that this patch fixes? The
> stable@...xes tags in that are wrong/incomplete so Jarkko's tree will
> need to be fixed before pushing to Linus anyway.

Sounds reasonable. I can hold the PR to rc6 and send it on Monday.

BR, Jarkko