Re: [PATCH v2] media:dvb-frontends:Remove dvb_pll_devcount and id module parameters.

From: Sean Young
Date: Fri Aug 02 2019 - 20:25:06 EST

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In reply to: Vandana BN: "Re: [PATCH v2] media:dvb-frontends:Remove dvb_pll_devcount and id module parameters."
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On Fri, Aug 02, 2019 at 12:20:19PM +0530, Vandana BN wrote:
>
> On 01/08/19 2:31 PM, Michael Ira Krufky wrote:
> > Sean,
> >
> > Please pardon the late reply. See my responses inline below:
> >
> > On Wed, Jul 24, 2019 at 1:36 AM Sean Young <sean@xxxxxxxx> 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?
> > Sean,
> >
> > This was to support DVB-T/C & ATSC/QAM-B cards that had multiple RF
> > input options intended to be used to connect an aerial and a Cable TV
> > input source simultaneously. It should not be removed.
>
> Hi Mike,
>
> Thanks for clarifying.
>
> This patch tries to fix global out of bounds reported by syzbot.
>
> 1st patch i submitted, checked for DVB_MAX_PLL before adding the device in dvb_pll_attach(), Akihiro pointed that this would put a limit on number of devices that can be attached.
>
> 2nd patch, was to remove the module parameters, as per suggestion from Akihiro.
>
> Should the module parameters use DEFINE_IDA and ida simple_get,ida_simple_remove, as suggested by Sean.
>
> Can you please suggest on how to fix it.

I had something like this in mind. This is compile-tested only.

Thanks,
Sean

Next message: David Miller: "Re: [PATCH v2 net] hv_sock: Fix hang when a connection is closed"
Previous message: Rob Clark: "Re: [PATCH AUTOSEL 5.2 42/76] drm/msm: stop abusing dma_map/unmap for cache"
In reply to: Vandana BN: "Re: [PATCH v2] media:dvb-frontends:Remove dvb_pll_devcount and id module parameters."
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