Messages in this thread | | | Subject | Re: [PATCH v7 1/5] tpm: dynamically allocate the allocated_banks array | From | Roberto Sassu <> | Date | Fri, 11 Jan 2019 08:53:00 +0100 |
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On 1/10/2019 6:38 PM, Jarkko Sakkinen wrote: > On Mon, Jan 07, 2019 at 11:06:33AM +0100, Roberto Sassu wrote: >> On 12/22/2018 1:03 AM, Jarkko Sakkinen wrote: >>> On Fri, Dec 21, 2018 at 10:40:09AM +0100, Roberto Sassu wrote: >>>> On 12/20/2018 3:55 PM, Jarkko Sakkinen wrote: >>>>> On Thu, Dec 13, 2018 at 11:29:41AM +0100, Roberto Sassu wrote: >>>>>> This patch renames active_banks (member of tpm_chip) to allocated_banks, >>>>>> stores the number of allocated PCR banks in nr_allocated_banks (new member >>>>>> of tpm_chip), and replaces the static array with a pointer to a dynamically >>>>>> allocated array. >>>>>> >>>>>> tpm2_get_pcr_allocation() determines if a PCR bank is allocated by checking >>>>>> the mask in the TPML_PCR_SELECTION structure returned by the TPM for >>>>>> TPM2_Get_Capability(). If a bank is not allocated, the TPM returns that >>>>>> bank in TPML_PCR_SELECTION, with all bits in the mask set to zero. In this >>>>>> case, the bank is not included in chip->allocated_banks, to avoid that TPM >>>>>> driver users unnecessarily calculate a digest for that bank. >>>>>> >>>>>> One PCR bank with algorithm set to SHA1 is always allocated for TPM 1.x. >>>>>> >>>>>> As a consequence of the introduction of nr_allocated_banks, >>>>>> tpm_pcr_extend() does not check anymore if the algorithm stored in tpm_chip >>>>>> is equal to zero. >>>>>> >>>>>> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> >>>>>> Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> >>>>>> --- >>>>>> drivers/char/tpm/tpm-chip.c | 1 + >>>>>> drivers/char/tpm/tpm-interface.c | 18 +++++++++-------- >>>>>> drivers/char/tpm/tpm.h | 3 ++- >>>>>> drivers/char/tpm/tpm1-cmd.c | 10 ++++++++++ >>>>>> drivers/char/tpm/tpm2-cmd.c | 34 ++++++++++++++++++++++---------- >>>>>> 5 files changed, 47 insertions(+), 19 deletions(-) >>>>>> >>>>>> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c >>>>>> index 32db84683c40..ce851c62bb68 100644 >>>>>> --- a/drivers/char/tpm/tpm-chip.c >>>>>> +++ b/drivers/char/tpm/tpm-chip.c >>>>>> @@ -160,6 +160,7 @@ static void tpm_dev_release(struct device *dev) >>>>>> kfree(chip->log.bios_event_log); >>>>>> kfree(chip->work_space.context_buf); >>>>>> kfree(chip->work_space.session_buf); >>>>>> + kfree(chip->allocated_banks); >>>>>> kfree(chip); >>>>>> } >>>>>> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c >>>>>> index d9439f9abe78..7b80919228be 100644 >>>>>> --- a/drivers/char/tpm/tpm-interface.c >>>>>> +++ b/drivers/char/tpm/tpm-interface.c >>>>>> @@ -488,8 +488,7 @@ EXPORT_SYMBOL_GPL(tpm_pcr_read); >>>>>> int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, const u8 *hash) >>>>>> { >>>>>> int rc; >>>>>> - struct tpm2_digest digest_list[ARRAY_SIZE(chip->active_banks)]; >>>>>> - u32 count = 0; >>>>>> + struct tpm2_digest *digest_list; >>>>>> int i; >>>>>> chip = tpm_find_get_ops(chip); >>>>>> @@ -497,16 +496,19 @@ int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, const u8 *hash) >>>>>> return -ENODEV; >>>>>> if (chip->flags & TPM_CHIP_FLAG_TPM2) { >>>>>> - memset(digest_list, 0, sizeof(digest_list)); >>>>>> + digest_list = kcalloc(chip->nr_allocated_banks, >>>>>> + sizeof(*digest_list), GFP_KERNEL); >>>>>> + if (!digest_list) >>>>>> + return -ENOMEM; >>>>> >>>>> You could preallocate digest list and place it to struct tpm_chip >>>>> instead of doing it everytime tpm_pcr_extend() called. >>>> >>>> This part will be removed with patch 5/5. >>> >>> Even if it did, it does not make this patch unbroken. >> >> Can two calls to tpm_pcr_extend() be executed at the same time? >> >> If yes, the digest list should be protected by a mutex. > > Good question: the answer is no. Mutex locking is done inside the > transmit flow ATM.
But data are copied before the mutex is locked. Can't a second call overwrite chip->preallocated_digest_list while the first call is still writing it?
Roberto
> /Jarkko >
-- HUAWEI TECHNOLOGIES Duesseldorf GmbH, HRB 56063 Managing Director: Bo PENG, Jian LI, Yanli SHI
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