tpm: Check outgoing command size

In tpm_sendrecv_command() the command buffer is passed in. If a mistake is
somehow made in setting this up, the size could be out of range. Add a
sanity check for this.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reported-by: Coverity (CID: 331152)

lib/tpm-common.c

@@ -176,6 +176,11 @@ u32 tpm_sendrecv_command(struct udevice *dev, const void *command,
 	}
 
 	size = tpm_command_size(command);
+
+	/* sanity check, which also helps coverity */
+	if (size > COMMAND_BUFFER_SIZE)
+		return log_msg_ret("size", -E2BIG);
+
 	log_debug("TPM request [size:%d]: ", size);
 	for (i = 0; i < size; i++)
 		log_debug("%02x ", ((u8 *)command)[i]);