Re: [PATCH v2] media:dvb-frontends:Remove dvb_pll_devcount and id module parameters.
From: Vandana BN
Date: Thu Aug 01 2019 - 04:53:19 EST
On 01/08/19 10:39 AM, Sean Young wrote:
> On Wed, Jul 24, 2019 at 06:36:35AM +0100, Sean Young wrote:
>> On Sat, Jul 20, 2019 at 11:43:02AM +0530, Vandana BN wrote:
>>> Syzbot reported global-out-of-bounds Read in dvb_pll_attach, while
>>> accessing id[dvb_pll_devcount], because dvb_pll_devcount was 65,
>>> that is more than size of 'id' which is DVB_PLL_MAX(64).
>>>
>>> Fix would be to check if DVB_PLL_MAX devices are attached and if so return
>>> NULL from dvb_pll_attach(). But this will put a limit on the number of
>>> devices that can be attached.
>>> Also dvb_pll_devcount and "id" module parameter are used for debugging
>>> purpose to override/force PLL type.
>>> So this patch removes these module parameters.
>>>
>>> Reported-by: syz...@xxxxxxxxxxxxxxxxxxxxxxxxx
>>>
>>> usb 1-1: dvb_usb_v2: will pass the complete MPEG2 transport stream to the
>>> software demuxer
>>> dvbdev: DVB: registering new adapter (774 Friio White ISDB-T USB2.0)
>>> usb 1-1: media controller created
>>> dvbdev: dvb_create_media_entity: media entity 'dvb-demux' registered.
>>> tc90522 0-0018: Toshiba TC90522 attached.
>>> usb 1-1: DVB: registering adapter 0 frontend 0 (Toshiba TC90522 ISDB-T
>>> module)...
>>> dvbdev: dvb_create_media_entity: media entity 'Toshiba TC90522 ISDB-T
>>> module' registered.
>>> ==================================================================
>>> BUG: KASAN: global-out-of-bounds in dvb_pll_attach+0x6c5/0x830
>>> drivers/media/dvb-frontends/dvb-pll.c:798
>>> Read of size 4 at addr ffffffff89c9e5e0 by task kworker/0:1/12
>>>
>>> CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.2.0-rc6+ #13
>>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
>>> Google 01/01/2011
>>> Workqueue: usb_hub_wq hub_event
>>> Call Trace:
>>> __dump_stack lib/dump_stack.c:77 [inline]
>>> dump_stack+0xca/0x13e lib/dump_stack.c:113
>>> print_address_description+0x67/0x231 mm/kasan/report.c:188
>>> __kasan_report.cold+0x1a/0x32 mm/kasan/report.c:317
>>> kasan_report+0xe/0x20 mm/kasan/common.c:614
>>> dvb_pll_attach+0x6c5/0x830 drivers/media/dvb-frontends/dvb-pll.c:798
>>> dvb_pll_probe+0xfe/0x174 drivers/media/dvb-frontends/dvb-pll.c:877
>>> i2c_device_probe+0x790/0xaa0 drivers/i2c/i2c-core-base.c:389
>>> really_probe+0x281/0x660 drivers/base/dd.c:509
>>> driver_probe_device+0x104/0x210 drivers/base/dd.c:670
>>> __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:777
>>> bus_for_each_drv+0x15c/0x1e0 drivers/base/bus.c:454
>>> __device_attach+0x217/0x360 drivers/base/dd.c:843
>>> bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
>>> device_add+0xae6/0x16f0 drivers/base/core.c:2111
>>> i2c_new_client_device+0x5b3/0xc40 drivers/i2c/i2c-core-base.c:778
>>> i2c_new_device+0x19/0x50 drivers/i2c/i2c-core-base.c:821
>>> dvb_module_probe+0xf9/0x220 drivers/media/dvb-core/dvbdev.c:985
>>> friio_tuner_attach+0x125/0x1d0 drivers/media/usb/dvb-usb-v2/gl861.c:536
>>> dvb_usbv2_adapter_frontend_init
>>> drivers/media/usb/dvb-usb-v2/dvb_usb_core.c:675 [inline]
>>> dvb_usbv2_adapter_init drivers/media/usb/dvb-usb-v2/dvb_usb_core.c:804
>>> [inline]
>>> dvb_usbv2_init drivers/media/usb/dvb-usb-v2/dvb_usb_core.c:865 [inline]
>>> dvb_usbv2_probe.cold+0x24dc/0x255d
>>> drivers/media/usb/dvb-usb-v2/dvb_usb_core.c:980
>>> usb_probe_interface+0x305/0x7a0 drivers/usb/core/driver.c:361
>>> really_probe+0x281/0x660 drivers/base/dd.c:509
>>> driver_probe_device+0x104/0x210 drivers/base/dd.c:670
>>> __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:777
>>> bus_for_each_drv+0x15c/0x1e0 drivers/base/bus.c:454
>>> __device_attach+0x217/0x360 drivers/base/dd.c:843
>>> bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
>>> device_add+0xae6/0x16f0 drivers/base/core.c:2111
>>> usb_set_configuration+0xdf6/0x1670 drivers/usb/core/message.c:2023
>>> generic_probe+0x9d/0xd5 drivers/usb/core/generic.c:210
>>> usb_probe_device+0x99/0x100 drivers/usb/core/driver.c:266
>>> really_probe+0x281/0x660 drivers/base/dd.c:509
>>> driver_probe_device+0x104/0x210 drivers/base/dd.c:670
>>> __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:777
>>> bus_for_each_drv+0x15c/0x1e0 drivers/base/bus.c:454
>>> __device_attach+0x217/0x360 drivers/base/dd.c:843
>>> bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
>>> device_add+0xae6/0x16f0 drivers/base/core.c:2111
>>> usb_new_device.cold+0x8c1/0x1016 drivers/usb/core/hub.c:2534
>>> hub_port_connect drivers/usb/core/hub.c:5089 [inline]
>>> hub_port_connect_change drivers/usb/core/hub.c:5204 [inline]
>>> port_event drivers/usb/core/hub.c:5350 [inline]
>>> hub_event+0x1ada/0x3590 drivers/usb/core/hub.c:5432
>>> process_one_work+0x905/0x1570 kernel/workqueue.c:2269
>>> process_scheduled_works kernel/workqueue.c:2331 [inline]
>>> worker_thread+0x7ab/0xe20 kernel/workqueue.c:2417
>>> kthread+0x30b/0x410 kernel/kthread.c:255
>>> ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
>>>
>>> The buggy address belongs to the variable:
>>> id+0x100/0x120
>>>
>>> Memory state around the buggy address:
>>> ffffffff89c9e480: fa fa fa fa 00 00 fa fa fa fa fa fa 00 00 00 00
>>> ffffffff89c9e500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>>>> ffffffff89c9e580: 00 00 00 00 00 00 00 00 00 00 00 00 fa fa fa fa
>>> ^
>>> ffffffff89c9e600: 04 fa fa fa fa fa fa fa 04 fa fa fa fa fa fa fa
>>> ffffffff89c9e680: 04 fa fa fa fa fa fa fa 04 fa fa fa fa fa fa fa
>>> ==================================================================
>>>
>>> Signed-off-by: Vandana BN <bnvandana@xxxxxxxxx>
>>> ---
>>> drivers/media/dvb-frontends/dvb-pll.c | 19 +++----------------
>>> 1 file changed, 3 insertions(+), 16 deletions(-)
>>>
>>> diff --git a/drivers/media/dvb-frontends/dvb-pll.c b/drivers/media/dvb-frontends/dvb-pll.c
>>> index ba0c49107bd2..c3a04751e9cf 100644
>>> --- a/drivers/media/dvb-frontends/dvb-pll.c
>>> +++ b/drivers/media/dvb-frontends/dvb-pll.c
>>> @@ -33,19 +33,11 @@ struct dvb_pll_priv {
>>> u32 bandwidth;
>>> };
>>>
>>> -#define DVB_PLL_MAX 64
>>> -
>>> -static unsigned int dvb_pll_devcount;
>>>
>>> static int debug;
>>> module_param(debug, int, 0644);
>>> MODULE_PARM_DESC(debug, "enable verbose debug messages");
>>>
>>> -static unsigned int id[DVB_PLL_MAX] =
>>> - { [ 0 ... (DVB_PLL_MAX-1) ] = DVB_PLL_UNDEFINED };
>>> -module_param_array(id, int, NULL, 0644);
>>> -MODULE_PARM_DESC(id, "force pll id to use (DEBUG ONLY)");
>>> -
>> Mike, you introduced this module parameter in:
>>
>> commit 05a4611b5d71ad6f968fdeef092c24914570898b
>> Author: Michael Krufky <mkrufky@xxxxxxxxxxx>
>> AuthorDate: Fri Sep 7 18:19:57 2007 -0300
>>
>> V4L/DVB (6228): dvb-pll: add module option to specify rf input
>>
>> Add a module option to dvb-pll, called "input" to specify which rf
>> input to use on devices with multiple rf inputs. If the module option
>> is not specified, then the driver will autoselect the rf input, as per
>> previous behavior.
>>
>> Signed-off-by: Michael Krufky <mkrufky@xxxxxxxxxxx>
>> Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxx>
>>
>> What was your motivation?
> dvb_pll_devcount only ever gets increased, so this only works for the
> first time a driver is loaded; after a usb replug or rmmod this does
> not work anymore since the dvb_pll_devcount will have moved on to the
> next entry. Considering it is broken maybe it should just be removed;
> also we have no answer from mkrufky yet.
>
> If this functionality is useful, then it should be implemented with
> an DEFINE_IDA() and ida_simpla_get(), but I'm not sure it's worth it
> when the functionality is probably unused. If it was used, someone
> would have noticed it was broken.
Thanks Sean,
I Will send updated patch addressing your review comments.
Regards,
Vandana.
>
> Sean