• Petr Vandrovec's avatar
    tpm: fix handling of the TPM 2.0 event logs · fd5c7869
    Petr Vandrovec authored
    When TPM2 log has entries with more than 3 digests, or with digests
    not listed in the log header, log gets misparsed, eventually
    leading to kernel complaint that code tried to vmalloc 512MB of
    memory (I have no idea what would happen on bigger system).
    
    So code should not parse only first 3 digests: both event header
    and event itself are already in memory, so we can parse any number
    of digests, as long as we do not try to parse whole memory when
    given count of 0xFFFFFFFF.
    
    So this change:
    
    * Rejects event entry with more digests than log header describes.
      Digest types should be unique, and all should be described in
      log header, so there cannot be more digests in the event than in
      the header.
    
    * Reject event entry with digest that is not described in the
      log header.  In theory code could hardcode information about
      digest IDs already assigned by TCG, but if firmware authors
      cannot get event log format right, why should anyone believe
      that they got event log content right.
    
    Cc: stable@vger.kernel.org
    Fixes: 4d23cc32 ("tpm: add securityfs support for TPM 2.0 firmware event log")
    Signed-off-by: default avatarPetr Vandrovec <petr@vmware.com>
    Reviewed-by: default avatarJarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
    Signed-off-by: default avatarJarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
    fd5c7869
tpm2_eventlog.c 5.19 KB