tpm: Use interface timeouts returned from the TPM

The TPM driver currently discards the interface timeout values returned
from the TPM. The check of the response packet needs to consider that
the return_code field is 0 on success and the size of the expected
packet is equivalent to the header size + u32 length indicator for the
TPM_GetCapability() result + 4 interface timeout indicators of type u32.
Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Signed-off-by: Rajiv Andrade <srajiv@linux.vnet.ibm.com>

drivers/char/tpm/tpm.c

@@ -545,9 +545,10 @@ void tpm_get_timeouts(struct tpm_chip *chip)
 	if (rc)
 		goto duration;
 
-	if (be32_to_cpu(tpm_cmd.header.out.length)
-	    != 4 * sizeof(u32))
-		goto duration;
+	if (be32_to_cpu(tpm_cmd.header.out.return_code) != 0 ||
+	    be32_to_cpu(tpm_cmd.header.out.length)
+	    != sizeof(tpm_cmd.header.out) + sizeof(u32) + 4 * sizeof(u32))
+		return;
 
 	timeout_cap = &tpm_cmd.params.getcap_out.cap.timeout;
 	/* Don't overwrite default if value is 0 */