Package: modemmanager Version: 0.4+git.20100624t180933.6e79d15-2 Severity: serious
I have been having trouble getting our reprap (open hardware 3D printer) connecting reliably. Sometimes the host control softare gets EBUSY and at other times it appears to suffer protocol violations during startup. The reprap shows up as a ttyUSB emulated serial device. EBUSY indicates that something else on the system is opening the serial port. Having investigated this, in particular grepping the logs, I see things like this: /var/log/daemon.log:Aug 4 14:04:09 zealot modem-manager: (ttyUSB0): probe requested by plugin 'Generic' /var/log/daemon.log:Aug 4 14:04:20 zealot modem-manager: (ttyUSB0) closing serial device... /var/log/daemon.log:Aug 4 14:04:21 zealot modem-manager: (ttyUSB0) opening serial device... /var/log/daemon.log:Aug 4 14:04:27 zealot modem-manager: (ttyUSB0) closing serial device... It is not appropriate for a package like modemmanager to unconditionally open and "probe" serial devices. Serial devices, including both conventional ttyS* devices and USB-serial adapters such as ttyUSB, might be connected to arbitrary hardware. Indeed serial ports are often used for connection to ad-hoc peripherals such as the microcontrollers controlling machine tools and other real-world physical systems. Sending "probe" messages to them might cause arbitrarily weird or dangerous behaviour, since such peripherals by their nature speak their own private protocols. Even opening the port might interfere with control software. The modemmanager package should therefore obtain permission before allowing probing of arbitrary serial ports. (Automatic probing, without permission, of "serial" ports which modemmanager knows, eg via the USB device ID or kernel device name, are actually modems is fine.) The default value for this permission must be "off". I don't know exactly how I got modemmanager installed, but the most likely cause is the Recommends from network-manager, which I do use on this system. I did try to get my GSM/HSPA modem connection working with network-manager, but failed; I use a simple shell script to invoke pppd by hand for that; so luckily for me I am able to deinstall modemmanager. Users who are using modemmanager for their network connection /and/ also trying to do machinery control with the same computer would probably benefit from a more selective workaround which disables the scan for certain devices. Severity justification: This behaviour of modemmanager can undoubtedly cause trouble for unrelated software on the system. It might cause machinery connected to the computer to malfunction, perhaps causing physical damage or even personal injury. These latter consequences are perhaps unlikely but it is difficult to analyse the risk because we can't know what protocols such hardware speaks. Thanks, Ian. -- To UNSUBSCRIBE, email to debian-bugs-rc-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
