Comment 36 for bug 468701

My problem is also a segfault of the cups usb backend:
mf@feistnas:~$ sudo /usr/lib/cups/backend/usb
DEBUG: list_devices_libusb
DEBUG: usb_find_busses=5
DEBUG: usb_find_devices=12
Segmentation fault
mf@feistnas:~$ sudo usb_printerid /dev/usb/lp0
GET_DEVICE_ID string:
Af���jb

o/com/ubuntu/Upstart
scom.ubuntu.Upstart0_6
s EmitEven
gsasbi2c-adapter-devi
mf@feistnas:~$ sudo usb_printerid /dev/usb/lp1
GET_DEVICE_ID string:
MFG:HEWLETT-PACKARD;MDL:DESKJET 930C;CMD:MLC,PCL,PML;CLASS:PRINTER;DESCRIPTION:Hewlett-Packard DeskJet 930C;SERN:ES03N1D2D4JJ;VSTATUS:$XB0$XC0,ff,DN,OFFF,CUT,K0,C0,SM,NR,KP000,CP000;VP:0800,FL,B0;VJ: ;
mf@feistnas:~$ lsusb
Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 002 Device 004: ID 04b4:fd11 Cypress Semiconductor Corp.
Bus 002 Device 002: ID 058f:9254 Alcor Micro Corp. Hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 005: ID 071d:2000 Eicon Networks Corp. Teledat Surf
Bus 001 Device 002: ID 050d:0231 Belkin Components
Bus 001 Device 004: ID 058f:6362 Alcor Micro Corp. Hi-Speed 21-in-1 Flash Card Reader/Writer (Internal/External)
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
mf@feistnas:~$ ls -l /dev/usb/lp* /dev/bus/usb/*/*
crw-rw-r-- 1 root vboxusers 189, 0 2010-05-03 21:20 /dev/bus/usb/001/001
crw-rw-r-- 1 root vboxusers 189, 1 2010-05-03 21:20 /dev/bus/usb/001/002
crw-rw-r-- 1 root vboxusers 189, 3 2010-05-03 21:20 /dev/bus/usb/001/004
crw-rw-r-- 1 root vboxusers 189, 4 2010-05-03 21:20 /dev/bus/usb/001/005
crw-rw-r-- 1 root vboxusers 189, 128 2010-05-03 21:20 /dev/bus/usb/002/001
crw-rw-r-- 1 root vboxusers 189, 129 2010-05-03 21:20 /dev/bus/usb/002/002
crw-rw---- 1 root lp 189, 130 2010-05-03 21:20 /dev/bus/usb/002/003
crw-rw-r-- 1 root vboxusers 189, 131 2010-05-03 21:20 /dev/bus/usb/002/004
crw-rw----+ 1 root lp 189, 132 2010-05-03 21:21 /dev/bus/usb/002/005
crw-rw-r-- 1 root vboxusers 189, 256 2010-05-03 21:20 /dev/bus/usb/003/001
crw-rw-r-- 1 root vboxusers 189, 384 2010-05-03 21:20 /dev/bus/usb/004/001
crw-rw-r-- 1 root vboxusers 189, 512 2010-05-03 21:20 /dev/bus/usb/005/001
crw-rw---- 1 root lp 180, 0 2010-05-03 21:20 /dev/usb/lp0
crw-rw---- 1 root lp 180, 1 2010-05-03 21:20 /dev/usb/lp1

It seems that the deviceid of usb/lp0 is messed up, like you can see in the hexdump:
mf@feistnas:~$ sudo usb_printerid /dev/usb/lp0 | hd
00000000 47 45 54 5f 44 45 56 49 43 45 5f 49 44 20 73 74 |GET_DEVICE_ID st|
00000010 72 69 6e 67 3a 0a 41 66 00 88 ff ff 6a 00 00 00 |ring:.Af....j...|
00000020 62 00 00 00 01 01 6f 00 13 00 00 00 2f 63 6f 6d |b.....o...../com|
00000030 2f 75 62 75 6e 74 75 2f 55 70 73 74 61 72 74 00 |/ubuntu/Upstart.|
00000040 00 00 00 00 02 01 73 00 15 00 00 00 63 6f 6d 2e |......s.....com.|
00000050 75 62 75 6e 74 75 2e 55 70 73 74 61 72 74 30 5f |ubuntu.Upstart0_|
00000060 36 00 00 00 03 01 73 00 09 00 00 00 45 6d 69 74 |6.....s.....Emit|
00000070 45 76 65 6e 74 00 00 00 00 00 00 00 08 01 67 00 |Event.........g.|
00000080 04 73 61 73 62 00 00 00 00 00 00 00 18 00 00 00 |.sasb...........|
00000090 69 32 63 2d 61 64 61 70 74 65 72 2d 64 65 76 69 |i2c-adapter-devi|
000000a0 0a |.|
The device /dev/usb/lp0 is a usb to parallel adapter. Attached to the adapter is an old Epson LQ 1170 (24 dot matrix printer).
Luckily the backend hp also supports my other printer and at the moment I configured the Epson LQ 1170 as parallel:/dev/usb/lp0 in cups.