V4L/DVB (10265): budget.c driver: Kernel oops: "BUG: unable to handle kernel paging request at ffffffff

I'm using a "Hauppauge WinTV-NOVA-T DVB card" of PCI id "13c2:1005" with
kernel 2.6.27.9.

I've recently experienced the following fairly consistent kernel oops on
startup in grundig_29504_401_tuner_set_params from budget.c. As you
might expect, following this failure, the card doesn't work.

I'm not a kernel developer, nevertheless I seem to have managed to track
this down to a non-existent initialisation of
budget->dvb_frontend->tuner_priv.

The attached patch fixes the problem for me (and I've managed to tune
the card successfully as a result), but I don't know of anyone else
using the driver so I can't test it on other people.

Please let me know if this works for you or if I've done something
terribly wrong ;-(

BUG: unable to handle kernel paging request at ffffffff
IP: [<f8981e11>] :budget:grundig_29504_401_tuner_set_params+0x3b/0xf8
*pde = 007e0067 *pte = 00000000
Oops: 0000 [#1] SMP
Modules linked in: bridge stp bnep rfcomm l2cap asb100 hwmon_vid hwmon
fuse ipt_REJECT nf_conntrack_ipv4 iptable_filter ip_tables ip6t_REJECT
xt_tcpudp nf_conntrack_ipv6 xt_state nf_conntrack ip6table_filter
ip6_tables x_tables ipv6 loop dm_multipath scsi_dh ppdev snd_cmipci
gameport snd_seq_dummy snd_seq_oss snd_seq_midi_event snd_seq
snd_pcm_oss snd_mixer_oss l64781 snd_pcm snd_page_alloc snd_opl3_lib
snd_timer parport_pc snd_hwdep parport btusb snd_mpu401_uart budget
budget_core snd_rawmidi bluetooth saa7146 snd_seq_device ttpci_eeprom
snd soundcore sr_mod i2c_sis96x cdrom dvb_core sis900 i2c_core floppy
pcspkr mii sata_sil sg dm_snapshot dm_zero dm_mirror dm_log dm_mod
pata_sis ata_generic pata_acpi libata sd_mod scsi_mod crc_t10dif ext3
jbd mbcache uhci_hcd ohci_hcd ehci_hcd [last unloaded: microcode]

Pid: 2319, comm: kdvb-fe-0 Not tainted (2.6.27.9-73.fc9.i686 #1)
EIP: 0060:[<f8981e11>] EFLAGS: 00010286 CPU: 0
EIP is at grundig_29504_401_tuner_set_params+0x3b/0xf8 [budget]
EAX: f6417f00 EBX: f6f53808 ECX: 00000000 EDX: ffffffff
ESI: f6f94404 EDI: f6417f00 EBP: f6417f10 ESP: f6417ef0
  DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068
Process kdvb-fe-0 (pid: 2319, ti=f6417000 task=f642b2c0 task.ti=f6417000)
Stack: f6e39800 00000000 00000004 f6417f00 c064523c f6f53808 f6f53800 f6f94404
        f6417f54 f8b2e45a f6417f24 00000286 f6417f4c f6417f38 00000000 00000286
        f6417f3c c064520f f642b2c0 f6417f6c c064456f 00000001 f6f94400 00000001
Call Trace:
  [<c064523c>] ? _spin_lock_irqsave+0x29/0x30
  [<f8b2e45a>] ? apply_frontend_param+0x27/0x357 [l64781]
  [<c064520f>] ? _spin_lock_irq+0x1c/0x20
  [<c064456f>] ? __down_common+0x91/0xbf
  [<f894f25d>] ? dvb_frontend_swzigzag_autotune+0x17d/0x1a4 [dvb_core]
  [<f894f780>] ? dvb_frontend_swzigzag+0x1ac/0x209 [dvb_core]
  [<f894fcc8>] ? dvb_frontend_thread+0x2eb/0x3b3 [dvb_core]
  [<c043c166>] ? autoremove_wake_function+0x0/0x33
  [<f894f9dd>] ? dvb_frontend_thread+0x0/0x3b3 [dvb_core]
  [<c043bec3>] ? kthread+0x3b/0x61
  [<c043be88>] ? kthread+0x0/0x61
  [<c040494b>] ? kernel_thread_helper+0x7/0x10
  =======================
Code: ec 14 8b 80 00 02 00 00 8b 93 08 02 00 00 8d 7d e4 8b 40 20 89 45
e0 31 c0 85 d2 f3 ab 8d 45 f0 66 c7 45 e8 04 00 89 45 ec 74 09 <0f> b6
02 66 89 45 e4 eb 06 66 c7 45 e4 61 00 8b 0e be 0a 8b 02
EIP: [<f8981e11>] grundig_29504_401_tuner_set_params+0x3b/0xf8 [budget]
SS:ESP 0068:f6417ef0

Signed-off-by: Oliver Endriss <o.endriss@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/dvb/ttpci/budget.c

@@ -470,6 +470,7 @@ static void frontend_init(struct budget *budget)
 		budget->dvb_frontend = dvb_attach(l64781_attach, &grundig_29504_401_config, &budget->i2c_adap);
 		if (budget->dvb_frontend) {
 			budget->dvb_frontend->ops.tuner_ops.set_params = grundig_29504_401_tuner_set_params;
+			budget->dvb_frontend->tuner_priv = NULL;
 			break;
 		}
 		break;