Date:   Fri, 4 Jan 2019 14:25:00 +0100
From:   Benjamin Tissoires <benjamin.tissoires@...hat.com>
To:     Anatoly Trosinenko <anatoly.trosinenko@...il.com>
Cc:     Jiri Kosina <jikos@...nel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        "open list:HID CORE LAYER" <linux-input@...r.kernel.org>,
        Roderick Colenbrander <thunderbird2k@...il.com>
Subject: Re: NULL pointer dereference when writing fuzzed data to /dev/uhid

Hi Anatoly,


On Fri, Jan 4, 2019 at 1:32 PM Anatoly Trosinenko
<anatoly.trosinenko@...il.com> wrote:
>
> Hello,
>
> When writing the attached file to /dev/uhid, a NULL dereference occurs
> in kernel. As I understand, the problem is not UHID-specific, but is
> related to HID subsystem.

Thanks for the report.
I wanted to tell you that I started investigating the other private
report you sent us, but couldn't find the time to properly come with a
fix as the fuzzed data is hard to discriminate from valid data.

A couple of notes though:
- writing to uhid needs to be done by root. Any distribution that
doesn't enforce that is doomed to have several security issues
- we could somehow reproduce those fuzzed data on a USB or Bluetooth
connection, but that would require physical access to the device, so
you are doomed also
- last IIRC, there was some attempts by the ChromeOS team to allow
access to the HID stack from the Chrome plugins, I don't know if this
is able to generate the issues.

On the specifics reported here:

>
> How to reproduce:
> 1) Checkout the fresh master branch of the Linux kernel (tested on
> commit 96d4f267e)
> 2) Compile it with the attached config (kvm-xfstests capable)
> 3) Take one of reproducers and execute
> cat /vtmp/repro > /dev/uhid
>
> What happens:
>
> For chicony.bin:
>
> root@...-xfstests:~# cat /vtmp/chicony.bin > /dev/uhid
> [   19.072703] BUG: unable to handle kernel NULL pointer dereference
> at 0000000000000002
> [   19.073371] #PF error: [normal kernel read fault]
> [   19.073755] PGD 8000000078b2c067 P4D 8000000078b2c067 PUD 0
> [   19.074223] Oops: 0000 [#1] SMP PTI
> [   19.074809] CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted
> 4.20.0-xfstests-10979-g96d4f267e40 #1
> [   19.075965] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
> BIOS 1.11.1-1ubuntu1 04/01/2014
> [   19.077599] Workqueue: events uhid_device_add_worker
> [   19.078019] RIP: 0010:ch_switch12_report_fixup+0x13/0x70

This driver expects the device to be connected on USB, and you are
triggering the oops because you are on uhid.
I am chasing the USB dependencies in most drivers, but this is a hard
task to do when I do not have access to the actual devices.

I guess one way of fixing that is to add a check for the actual
transport driver during probe:
hid_is_using_ll_driver(hdev, &usb_hid_driver)

Patches are welcome :)

> [   19.078462] Code: 49 8b 00 3e 80 60 20 df b8 01 00 00 00 c3 66 0f
> 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 8b 8f 48 19 00 00 48 89 f0 48
> 8b 49 d8 <80> 79 02 01 74 01 c3 81 7f 3c 21 14 00 00 75 f6 83 3a 7f 76
> f1 80
> [   19.080103] RSP: 0018:ffffa1d880367c48 EFLAGS: 00010286
> [   19.080541] RAX: ffff9b653d27b180 RBX: ffff9b653a6fb948 RCX: 0000000000000000
> [   19.081133] RDX: ffffa1d880367c5c RSI: ffff9b653d27b180 RDI: ffff9b653a6fa000
> [   19.081780] RBP: ffff9b653d27b180 R08: 000000064992eed0 R09: 0000000000000000
> [   19.082409] R10: 0000000000000000 R11: 0000000000000000 R12: ffff9b653a6fa000
> [   19.083017] R13: ffffffff83f14510 R14: ffffffff83f14440 R15: 0000000000000000
> [   19.083619] FS:  0000000000000000(0000) GS:ffff9b653fc00000(0000)
> knlGS:0000000000000000
> [   19.084362] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   19.085164] CR2: 0000000000000002 CR3: 00000000788b8004 CR4: 0000000000360ef0
> [   19.085789] Call Trace:
> [   19.086011]  hid_open_report+0x81/0x2c0
> [   19.086341]  hid_device_probe+0x135/0x160
> [   19.086754]  ? __driver_attach+0x110/0x110
> [   19.087109]  really_probe+0xe0/0x390
> [   19.087411]  ? __driver_attach+0x110/0x110
> [   19.087782]  bus_for_each_drv+0x78/0xc0
> [   19.088134]  __device_attach+0xcc/0x130
> [   19.088477]  bus_probe_device+0x9f/0xb0
> [   19.088832]  device_add+0x422/0x680
> [   19.089144]  ? __debugfs_create_file+0xb5/0xf0
> [   19.089536]  hid_add_device+0xec/0x280
> [   19.089880]  uhid_device_add_worker+0x15/0x60
> [   19.090270]  process_one_work+0x238/0x5d0
> [   19.090627]  worker_thread+0x3d/0x390
> [   19.090959]  ? process_one_work+0x5d0/0x5d0
> [   19.091331]  kthread+0x121/0x140
> [   19.096732]  ? __kthread_create_on_node+0x1a0/0x1a0
> [   19.097164]  ret_from_fork+0x3a/0x50
> [   19.097483] CR2: 0000000000000002
> [   19.097779] ---[ end trace 1b547acaae113039 ]---
> [   19.098186] RIP: 0010:ch_switch12_report_fixup+0x13/0x70
> [   19.098621] Code: 49 8b 00 3e 80 60 20 df b8 01 00 00 00 c3 66 0f
> 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 8b 8f 48 19 00 00 48 89 f0 48
> 8b 49 d8 <80> 79 02 01 74 01 c3 81 7f 3c 21 14 00 00 75 f6 83 3a 7f 76
> f1 80
> [   19.100251] RSP: 0018:ffffa1d880367c48 EFLAGS: 00010286
> [   19.100707] RAX: ffff9b653d27b180 RBX: ffff9b653a6fb948 RCX: 0000000000000000
> [   19.101321] RDX: ffffa1d880367c5c RSI: ffff9b653d27b180 RDI: ffff9b653a6fa000
> [   19.102448] RBP: ffff9b653d27b180 R08: 000000064992eed0 R09: 0000000000000000
> [   19.103029] R10: 0000000000000000 R11: 0000000000000000 R12: ffff9b653a6fa000
> [   19.103601] R13: ffffffff83f14510 R14: ffffffff83f14440 R15: 0000000000000000
> [   19.104173] FS:  0000000000000000(0000) GS:ffff9b653fc00000(0000)
> knlGS:0000000000000000
> [   19.104823] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   19.105289] CR2: 0000000000000002 CR3: 00000000788b8004 CR4: 0000000000360ef0
> [   19.105864] BUG: sleeping function called from invalid context at
> include/linux/percpu-rwsem.h:34
> [   19.106578] in_atomic(): 0, irqs_disabled(): 1, pid: 5, name: kworker/0:0
> [   19.107671] INFO: lockdep is turned off.
> [   19.108384] irq event stamp: 3576
> [   19.108976] hardirqs last  enabled at (3575): [<ffffffff82e01ed5>]
> __kmalloc_track_caller+0x185/0x310
> [   19.112970] hardirqs last disabled at (3576): [<ffffffff82c015f4>]
> trace_hardirqs_off_thunk+0x1a/0x1c
> [   19.114557] softirqs last  enabled at (3504): [<ffffffff834002b1>]
> peernet2id+0x51/0x80
> [   19.115897] softirqs last disabled at (3502): [<ffffffff83400292>]
> peernet2id+0x32/0x80
> [   19.117319] CPU: 0 PID: 5 Comm: kworker/0:0 Tainted: G      D
>     4.20.0-xfstests-10979-g96d4f267e40 #1
> [   19.118739] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
> BIOS 1.11.1-1ubuntu1 04/01/2014
> [   19.120049] Workqueue: events uhid_device_add_worker
> [   19.120767] Call Trace:
> [   19.121127]  dump_stack+0x67/0x90
> [   19.121622]  ___might_sleep.cold.13+0x9f/0xaf
> [   19.122278]  exit_signals+0x1c/0x200
> [   19.122792]  do_exit+0xac/0xaf0
> [   19.123619]  ? process_one_work+0x5d0/0x5d0
> [   19.124520]  ? kthread+0x121/0x140
> [   19.125050]  rewind_stack_do_exit+0x17/0x20
>
> For sony.bin:
>
> root@...-xfstests:~# cat /vtmp/sony.bin > /dev/uhid
> [   16.891931] sony 0003:054C:1000.0001: unknown main item tag 0x0
> [   16.892432] sony 0003:054C:1000.0001: unknown main item tag 0x0
> [   16.892894] sony 0003:054C:1000.0001: unknown main item tag 0x0
> [   16.893362] sony 0003:054C:1000.0001: unknown main item tag 0x0
> [   16.893844] sony 0003:054C:1000.0001: unknown main item tag 0x0
> [   16.895389] sony 0003:054C:1000.0001: unknown main item tag 0x0
> [   16.898165] sony 0003:054C:1000.0001: ignoring exceeding usage max
> [   16.901190] sony 0003:054C:1000.0001: unknown main item tag 0x0
> [   16.903797] sony 0003:054C:1000.0001: unknown main item tag 0x0
> [   16.906401] sony 0003:054C:1000.0001: unknown main item tag 0x0
> [   16.908957] sony 0003:054C:1000.0001: unknown main item tag 0x0
> [   16.911449] sony 0003:054C:1000.0001: unknown main item tag 0x0
> [   16.913936] sony 0003:054C:1000.0001: unknown main item tag 0x1
> [   16.916551] sony 0003:054C:1000.0001: unknown main item tag 0x0
> [   16.918454] sony 0003:054C:1000.0001: unknown main item tag 0x0
> [   16.919743] sony 0003:054C:1000.0001: unknown main item tag 0x4
> [   16.920834] sony 0003:054C:1000.0001: unknown main item tag 0xe
> [   16.921904] sony 0003:054C:1000.0001: unknown main item tag 0xe
> [   16.923006] sony 0003:054C:1000.0001: unknown main item tag 0x0
> [   16.924082] sony 0003:054C:1000.0001: unknown main item tag 0x2
> [   16.925195] sony 0003:054C:1000.0001: unknown main item tag 0x0
> [   16.926289] sony 0003:054C:1000.0001: unknown main item tag 0x0
> [   16.927400] sony 0003:054C:1000.0001: unknown main item tag 0x0
> [   16.928546] BUG: unable to handle kernel NULL pointer dereference
> at 0000000000000028
> [   16.929951] #PF error: [normal kernel read fault]
> [   16.930884] PGD 800000007a52b067 P4D 800000007a52b067 PUD 0
> [   16.931836] Oops: 0000 [#1] SMP PTI
> [   16.932437] CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted
> 4.20.0-xfstests-10979-g96d4f267e40 #1
> [   16.933752] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
> BIOS 1.11.1-1ubuntu1 04/01/2014
> [   16.935372] Workqueue: events uhid_device_add_worker
> [   16.936321] RIP: 0010:hid_validate_values+0x48/0x110

In a sense, it's good to have a fault there because this was added to
make sure we do not blindly accept any data. The fact that it doesn't
fail gracefully is a sign that there is something else.
Maybe Roderick could have a look?

Cheers,
Benjamin

> [   16.937690] Code: 4c 69 ce 03 01 00 00 4a 8d 44 08 0c 48 8b 44 c7
> 08 48 85 c0 0f 84 a9 00 00 00 39 88 30 08 00 00 76 53 41 89 c9 4e 8b
> 4c c8 30 <45> 39 41 28 72 69 48 83 c4 08 c3 89 f6 48 69 c6 18 08 00 00
> 48 8b
> [   16.941067] RSP: 0018:ffffb2c880367ab0 EFLAGS: 00010286
> [   16.941935] RAX: ffff8d54b881c870 RBX: ffff8d54b881dd08 RCX: 0000000000000000
> [   16.943203] RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff8d54b881c000
> [   16.945406] RBP: ffff8d54bacb3580 R08: 0000000000000007 R09: 0000000000000000
> [   16.946590] R10: 0000000000000000 R11: ffff8d54b80293e6 R12: ffff8d54b881c000
> [   16.947668] R13: dead000000000100 R14: ffff8d54b881c000 R15: ffff8d54ba4fb818
> [   16.948765] FS:  0000000000000000(0000) GS:ffff8d54bfc00000(0000)
> knlGS:0000000000000000
> [   16.949838] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   16.950663] CR2: 0000000000000028 CR3: 000000007a4e8002 CR4: 0000000000360ef0
> [   16.951513] Call Trace:
> [   16.951870]  sony_input_configured+0xd6d/0x1060
> [   16.952608]  ? kobject_set_name_vargs+0x6f/0x90
> [   16.953257]  ? dev_set_name+0x57/0x70
> [   16.953783]  ? init_timer_key+0xed/0x120
> [   16.954353]  hidinput_connect+0x2fb/0x89b
> [   16.954974]  hid_connect+0x2f3/0x370
> [   16.955489]  hid_hw_start+0x38/0x60
> [   16.956052]  sony_probe+0xba/0x160
> [   16.956541]  hid_device_probe+0xf7/0x160
> [   16.957103]  ? __driver_attach+0x110/0x110
> [   16.957689]  really_probe+0xe0/0x390
> [   16.958206]  ? __driver_attach+0x110/0x110
> [   16.958797]  bus_for_each_drv+0x78/0xc0
> [   16.959290]  __device_attach+0xcc/0x130
> [   16.959832]  bus_probe_device+0x9f/0xb0
> [   16.960407]  device_add+0x422/0x680
> [   16.960772]  ? __debugfs_create_file+0xb5/0xf0
> [   16.962459]  hid_add_device+0xec/0x280
> [   16.963517]  uhid_device_add_worker+0x15/0x60
> [   16.964304]  process_one_work+0x238/0x5d0
> [   16.965062]  worker_thread+0x3d/0x390
> [   16.965737]  ? process_one_work+0x5d0/0x5d0
> [   16.966499]  kthread+0x121/0x140
> [   16.967089]  ? __kthread_create_on_node+0x1a0/0x1a0
> [   16.967988]  ret_from_fork+0x3a/0x50
> [   16.968742] CR2: 0000000000000028
> [   16.969394] ---[ end trace bc79f619177a8c3e ]---
> [   16.970267] RIP: 0010:hid_validate_values+0x48/0x110
> [   16.971167] Code: 4c 69 ce 03 01 00 00 4a 8d 44 08 0c 48 8b 44 c7
> 08 48 85 c0 0f 84 a9 00 00 00 39 88 30 08 00 00 76 53 41 89 c9 4e 8b
> 4c c8 30 <45> 39 41 28 72 69 48 83 c4 08 c3 89 f6 48 69 c6 18 08 00 00
> 48 8b
> [   16.974023] RSP: 0018:ffffb2c880367ab0 EFLAGS: 00010286
> [   16.974805] RAX: ffff8d54b881c870 RBX: ffff8d54b881dd08 RCX: 0000000000000000
> [   16.975925] RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff8d54b881c000
> [   16.977035] RBP: ffff8d54bacb3580 R08: 0000000000000007 R09: 0000000000000000
> [   16.978269] R10: 0000000000000000 R11: ffff8d54b80293e6 R12: ffff8d54b881c000
> [   16.979446] R13: dead000000000100 R14: ffff8d54b881c000 R15: ffff8d54ba4fb818
> [   16.980503] FS:  0000000000000000(0000) GS:ffff8d54bfc00000(0000)
> knlGS:0000000000000000
> [   16.981675] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   16.982566] CR2: 0000000000000028 CR3: 000000007a4e8002 CR4: 0000000000360ef0
> [   16.983712] BUG: sleeping function called from invalid context at
> include/linux/percpu-rwsem.h:34
> [   16.985362] in_atomic(): 0, irqs_disabled(): 1, pid: 5, name: kworker/0:0
> [   16.985947] INFO: lockdep is turned off.
> [   16.986296] irq event stamp: 4040
> [   16.986584] hardirqs last  enabled at (4039): [<ffffffffab201ed5>]
> __kmalloc_track_caller+0x185/0x310
> [   16.987354] hardirqs last disabled at (4040): [<ffffffffab0015f4>]
> trace_hardirqs_off_thunk+0x1a/0x1c
> [   16.988522] softirqs last  enabled at (3962): [<ffffffffabc0032f>]
> __do_softirq+0x32f/0x440
> [   16.989788] softirqs last disabled at (3955): [<ffffffffab0b32f6>]
> irq_exit+0xa6/0xe0
> [   16.992028] CPU: 0 PID: 5 Comm: kworker/0:0 Tainted: G      D
>     4.20.0-xfstests-10979-g96d4f267e40 #1
> [   16.993354] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
> BIOS 1.11.1-1ubuntu1 04/01/2014
> [   16.994960] Workqueue: events uhid_device_add_worker
> [   16.996048] Call Trace:
> [   16.996593]  dump_stack+0x67/0x90
> [   16.997203]  ___might_sleep.cold.13+0x9f/0xaf
> [   16.998004]  exit_signals+0x1c/0x200
> [   16.998660]  do_exit+0xac/0xaf0
> [   16.999232]  ? process_one_work+0x5d0/0x5d0
> [   16.999987]  ? kthread+0x121/0x140
> [   17.000709]  rewind_stack_do_exit+0x17/0x20
>
>
> Best regards
> Anatoly

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