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SubjectRe: [PATCH v5 2/7] tpm: remove definition of TPM2_ACTIVE_PCR_BANKS
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On 11/16/2018 2:38 PM, Jarkko Sakkinen wrote:
> On Wed, Nov 14, 2018 at 04:31:03PM +0100, Roberto Sassu wrote:
>> tcg_efi_specid_event and tcg_pcr_event2 declaration contains static arrays
>> for a list of hash algorithms used for event logs and event log digests.
>>
>> However, according to TCG EFI Protocol Specification, these arrays have
>> variable sizes. Setting the array size to zero or 3 does not make any
>> difference, because the parser has to adjust the offset depending on the
>> actual array size to access structure members after the static arrays.
>>
>> Thus, this patch removes the declaration of TPM2_ACTIVE_PCR_BANKS and sets
>> the array size to zero.
>>
>> Fixes: 4d23cc323cdb ("tpm: add securityfs support for TPM 2.0 firmware
>> event log")
>>
>> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
>> ---
>> include/linux/tpm_eventlog.h | 5 ++---
>> 1 file changed, 2 insertions(+), 3 deletions(-)
>>
>> diff --git a/include/linux/tpm_eventlog.h b/include/linux/tpm_eventlog.h
>> index 20d9da77fc11..3d5d162f09cc 100644
>> --- a/include/linux/tpm_eventlog.h
>> +++ b/include/linux/tpm_eventlog.h
>> @@ -8,7 +8,6 @@
>> #define TCG_EVENT_NAME_LEN_MAX 255
>> #define MAX_TEXT_EVENT 1000 /* Max event string length */
>> #define ACPI_TCPA_SIG "TCPA" /* 0x41504354 /'TCPA' */
>> -#define TPM2_ACTIVE_PCR_BANKS 3
>>
>> #define EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2 0x1
>> #define EFI_TCG2_EVENT_LOG_FORMAT_TCG_2 0x2
>> @@ -90,7 +89,7 @@ struct tcg_efi_specid_event {
>> u8 spec_errata;
>> u8 uintnsize;
>> u32 num_algs;
>> - struct tcg_efi_specid_event_algs digest_sizes[TPM2_ACTIVE_PCR_BANKS];
>> + struct tcg_efi_specid_event_algs digest_sizes[0];
>> u8 vendor_info_size;
>> u8 vendor_info[0];
>> } __packed;
>> @@ -117,7 +116,7 @@ struct tcg_pcr_event2 {
>> u32 pcr_idx;
>> u32 event_type;
>> u32 count;
>> - struct tpm2_digest digests[TPM2_ACTIVE_PCR_BANKS];
>> + struct tpm2_digest digests[0];
>> struct tcg_event_field event;
>> } __packed;
>>
>> --
>> 2.17.1
>>
>
> NAK for the same reason as last time.

I added this comment to include/linux/tpm_eventlog.h:

/*
* http://www.trustedcomputinggroup.org/tcg-efi-protocol-specification/
*
* Set the size of 'digest_sizes' and 'digests', members of
tcg_efi_specid_event
* and tcg_pcr_event2, to zero. Structures with variable-sized arrays
placed
* midway are not suitable for type casting.
*/

Is it ok?

Thanks

Roberto


> /Jarkko
>

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