BUG: unable to handle kernel NULL pointer dereference at 00000002
IP: [<f85c8c36>] acm_ctrl_msg.clone.13+0x36/0x70 [cdc_acm]
*pde = 30599067 *pte = 00000000 
Oops: 0000 [#1] SMP 
last sysfs file: /sys/devices/pci0000:00/0000:00:1d.0/usb2/idVendor
Modules linked in: ppp_deflate zlib_deflate bsd_comp ppp_async crc_ccitt cdc_acm cdc_wdm snd_hrtimer binfmt_misc vboxnetadp vboxnetflt vboxdrv parport_pc ppdev snd_hda_codec_realtek arc4 ath9k snd_hda_intel snd_hda_codec snd_hwdep snd_pcm mac80211 snd_seq_midi snd_rawmidi snd_seq_midi_event i915 snd_seq ath9k_common joydev ath9k_hw snd_timer uvcvideo snd_seq_device ath videodev cfg80211 psmouse drm_kms_helper snd serio_raw drm soundcore snd_page_alloc i2c_algo_bit video lp parport ahci libahci atl1c

Pid: 483, comm: modem-manager Not tainted 2.6.38-8-generic #41-Ubuntu Acer             AO532h          /AO532h          
EIP: 0060:[<f85c8c36>] EFLAGS: 00010286 CPU: 1
EIP is at acm_ctrl_msg.clone.13+0x36/0x70 [cdc_acm]
EAX: c74e0800 EBX: 00000000 ECX: 00000022 EDX: ce780000
ESI: 00000000 EDI: 00000000 EBP: f04e5e80 ESP: f04e5e60
 DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
Process modem-manager (pid: 483, ti=f04e4000 task=f045a5e0 task.ti=f04e4000)
Stack:
 fffffff5 e781d400 e781d41c 00000000 00000000 00001388 c74e7000 00000010
 f04e5ea4 f85c9974 00000000 00000000 00000000 00000296 c74e7000 d1788000
 c74e700c f04e5eb8 f85c9aa7 d1788000 00000000 f6ea5900 f04e5f44 c1301f2f
Call Trace:
 [<f85c9974>] acm_port_down+0x64/0x100 [cdc_acm]
 [<f85c9aa7>] acm_tty_close+0x67/0xb0 [cdc_acm]
 [<c1301f2f>] tty_release+0x10f/0x4e0
 [<c112794f>] ? do_readv_writev+0x14f/0x190
 [<c1128275>] __fput+0x95/0x1c0
 [<c11283bd>] fput+0x1d/0x30
 [<c11250fe>] filp_close+0x4e/0x70
 [<c1125925>] sys_close+0x75/0xd0
 [<c1509c24>] syscall_call+0x7/0xb
 [<c1500000>] ? print_cpu_info+0xb3/0x126
Code: 26 00 0f b7 75 10 89 d3 8b 10 0f b6 c9 89 74 24 10 8b 75 0c c7 44 24 14 88 13 00 00 c1 e2 08 89 74 24 0c 8b 1b 81 ca 00 00 00 80 <0f> b6 5b 02 c7 04 24 21 00 00 00 89 5c 24 08 0f b7 5d 08 89 5c 
EIP: [<f85c8c36>] acm_ctrl_msg.clone.13+0x36/0x70 [cdc_acm] SS:ESP 0068:f04e5e60
CR2: 0000000000000002
---[ end trace 5a2f54156c13c619 ]---