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

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Date:   Thu, 3 Aug 2023 15:50:44 +0200
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     Mario Limonciello <mario.limonciello@....com>
Cc:     Jarkko Sakkinen <jarkko@...nel.org>, 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 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.

Jason