[jarkko-tpmdd:tpm2-session 14/14] security/keys/trusted-keys/trusted_tpm2.c:489:21: warning: the comparison will always evaluate as 'true' for the address of 'blobauth' will never be NULL

[kernel test robot <lkp@intel.com>]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-tpmdd.git tpm2-session
head:   8443d24da35ca59b7be6056fa1ebe74070eb9e4a
commit: 8443d24da35ca59b7be6056fa1ebe74070eb9e4a [14/14] keys, trusted: Remove redundant helper
config: x86_64-rhel-9.4-func (https://download.01.org/0day-ci/archive/20250923/202509230748.evWsUrty-lkp@intel.com/config)
compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250923/202509230748.evWsUrty-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202509230748.evWsUrty-lkp@intel.com/

All warnings (new ones prefixed by >>):

   security/keys/trusted-keys/trusted_tpm2.c: In function 'tpm2_unseal_cmd':
>> security/keys/trusted-keys/trusted_tpm2.c:489:21: warning: the comparison will always evaluate as 'true' for the address of 'blobauth' will never be NULL [-Waddress]
     489 |                 if (options->blobauth)
         |                     ^~~~~~~
   In file included from security/keys/trusted-keys/trusted_tpm2.c:14:
   include/keys/trusted-type.h:41:23: note: 'blobauth' declared here
      41 |         unsigned char blobauth[TPM_DIGEST_SIZE];
         |                       ^~~~~~~~


vim +489 security/keys/trusted-keys/trusted_tpm2.c

   437	
   438	/**
   439	 * tpm2_unseal_cmd() - execute a TPM2_Unload command
   440	 *
   441	 * @chip: TPM chip to use
   442	 * @payload: the key data in clear and encrypted form
   443	 * @options: authentication values and other options
   444	 * @blob_handle: blob handle
   445	 *
   446	 * Return: 0 on success
   447	 *         -EPERM on tpm error status
   448	 *         < 0 error from tpm_send
   449	 */
   450	static int tpm2_unseal_cmd(struct tpm_chip *chip,
   451				   struct trusted_key_payload *payload,
   452				   struct trusted_key_options *options,
   453				   u32 blob_handle)
   454	{
   455		struct tpm_header *head;
   456		struct tpm_buf buf;
   457		u16 data_len;
   458		int offset;
   459		u8 *data;
   460		int rc;
   461	
   462		rc = tpm2_start_auth_session(chip);
   463		if (rc)
   464			return rc;
   465	
   466		rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_UNSEAL);
   467		if (rc) {
   468			tpm2_end_auth_session(chip);
   469			return rc;
   470		}
   471	
   472		tpm_buf_append_name(chip, &buf, blob_handle, NULL);
   473	
   474		if (!options->policyhandle) {
   475			tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_ENCRYPT,
   476						    options->blobauth,
   477						    options->blobauth_len);
   478		} else {
   479			/*
   480			 * The policy session is generated outside the kernel, and thus
   481			 * the password will end up being unencrypted on the bus, as
   482			 * HMAC nonce cannot be calculated for it.
   483			 */
   484			tpm_buf_append_u32(&buf, 9 + options->blobauth_len);
   485			tpm_buf_append_u32(&buf, options->policyhandle);
   486			tpm_buf_append_u16(&buf, 0);
   487			tpm_buf_append_u8(&buf, 0);
   488			tpm_buf_append_u16(&buf, options->blobauth_len);
 > 489			if (options->blobauth)
   490				tpm_buf_append(&buf, options->blobauth, options->blobauth_len);
   491			if (tpm2_chip_auth(chip)) {
   492				tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_ENCRYPT, NULL, 0);
   493			} else  {
   494				offset = buf.handles * 4 + TPM_HEADER_SIZE;
   495				head = (struct tpm_header *)buf.data;
   496				if (tpm_buf_length(&buf) == offset)
   497					head->tag = cpu_to_be16(TPM2_ST_NO_SESSIONS);
   498			}
   499		}
   500	
   501		tpm_buf_fill_hmac_session(chip, &buf);
   502		rc = tpm_transmit_cmd(chip, &buf, 6, "unsealing");
   503		rc = tpm_buf_check_hmac_response(chip, &buf, rc);
   504	
   505		if (!rc) {
   506			data_len = be16_to_cpup(
   507				(__be16 *) &buf.data[TPM_HEADER_SIZE + 4]);
   508			if (data_len < MIN_KEY_SIZE ||  data_len > MAX_KEY_SIZE) {
   509				rc = -EFAULT;
   510				goto out;
   511			}
   512	
   513			if (tpm_buf_length(&buf) < TPM_HEADER_SIZE + 6 + data_len) {
   514				rc = -EFAULT;
   515				goto out;
   516			}
   517			data = &buf.data[TPM_HEADER_SIZE + 6];
   518	
   519			if (payload->old_format) {
   520				/* migratable flag is at the end of the key */
   521				memcpy(payload->key, data, data_len - 1);
   522				payload->key_len = data_len - 1;
   523				payload->migratable = data[data_len - 1];
   524			} else {
   525				/*
   526				 * migratable flag already collected from key
   527				 * attributes
   528				 */
   529				memcpy(payload->key, data, data_len);
   530				payload->key_len = data_len;
   531			}
   532		}
   533	
   534	out:
   535		tpm_buf_destroy(&buf);
   536		return tpm_ret_to_err(rc);
   537	}
   538	

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