Re: [PATCH v2] HID: usbhid: fix out-of-bounds bug

[Andrey Konovalov]

On Tue, Oct 10, 2017 at 9:25 AM, Jaejoong Kim <climbbb.kim@xxxxxxxxx> wrote:
> Hi,
>
> To. Jiri, Alan,
>
> Could you please review this patch?
>
> To. Andey,
>
> Could you please test with this patch for KASAN OOB error?

Hi!

Yes, your patch fixes the issue.

Thanks!

Tested-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>

>
> Thanks, jaejoong
>
> 2017-09-28 19:16 GMT+09:00 Jaejoong Kim <climbbb.kim@xxxxxxxxx>:
>> The hid descriptor identifies the length and type of subordinate
>> descriptors for a device. If the received hid descriptor is smaller than
>> the size of the struct hid_descriptor, it is possible to cause
>> out-of-bounds.
>>
>> In addition, if bNumDescriptors of the hid descriptor have an incorrect
>> value, this can also cause out-of-bounds while approaching hdesc->desc[n].
>>
>> So check the size of hid descriptor and bNumDescriptors.
>>
>>         BUG: KASAN: slab-out-of-bounds in usbhid_parse+0x9b1/0xa20
>>         Read of size 1 at addr ffff88006c5f8edf by task kworker/1:2/1261
>>
>>         CPU: 1 PID: 1261 Comm: kworker/1:2 Not tainted
>>         4.14.0-rc1-42251-gebb2c2437d80 #169
>>         Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
>>         Workqueue: usb_hub_wq hub_event
>>         Call Trace:
>>         __dump_stack lib/dump_stack.c:16
>>         dump_stack+0x292/0x395 lib/dump_stack.c:52
>>         print_address_description+0x78/0x280 mm/kasan/report.c:252
>>         kasan_report_error mm/kasan/report.c:351
>>         kasan_report+0x22f/0x340 mm/kasan/report.c:409
>>         __asan_report_load1_noabort+0x19/0x20 mm/kasan/report.c:427
>>         usbhid_parse+0x9b1/0xa20 drivers/hid/usbhid/hid-core.c:1004
>>         hid_add_device+0x16b/0xb30 drivers/hid/hid-core.c:2944
>>         usbhid_probe+0xc28/0x1100 drivers/hid/usbhid/hid-core.c:1369
>>         usb_probe_interface+0x35d/0x8e0 drivers/usb/core/driver.c:361
>>         really_probe drivers/base/dd.c:413
>>         driver_probe_device+0x610/0xa00 drivers/base/dd.c:557
>>         __device_attach_driver+0x230/0x290 drivers/base/dd.c:653
>>         bus_for_each_drv+0x161/0x210 drivers/base/bus.c:463
>>         __device_attach+0x26e/0x3d0 drivers/base/dd.c:710
>>         device_initial_probe+0x1f/0x30 drivers/base/dd.c:757
>>         bus_probe_device+0x1eb/0x290 drivers/base/bus.c:523
>>         device_add+0xd0b/0x1660 drivers/base/core.c:1835
>>         usb_set_configuration+0x104e/0x1870 drivers/usb/core/message.c:1932
>>         generic_probe+0x73/0xe0 drivers/usb/core/generic.c:174
>>         usb_probe_device+0xaf/0xe0 drivers/usb/core/driver.c:266
>>         really_probe drivers/base/dd.c:413
>>         driver_probe_device+0x610/0xa00 drivers/base/dd.c:557
>>         __device_attach_driver+0x230/0x290 drivers/base/dd.c:653
>>         bus_for_each_drv+0x161/0x210 drivers/base/bus.c:463
>>         __device_attach+0x26e/0x3d0 drivers/base/dd.c:710
>>         device_initial_probe+0x1f/0x30 drivers/base/dd.c:757
>>         bus_probe_device+0x1eb/0x290 drivers/base/bus.c:523
>>         device_add+0xd0b/0x1660 drivers/base/core.c:1835
>>         usb_new_device+0x7b8/0x1020 drivers/usb/core/hub.c:2457
>>         hub_port_connect drivers/usb/core/hub.c:4903
>>         hub_port_connect_change drivers/usb/core/hub.c:5009
>>         port_event drivers/usb/core/hub.c:5115
>>         hub_event+0x194d/0x3740 drivers/usb/core/hub.c:5195
>>         process_one_work+0xc7f/0x1db0 kernel/workqueue.c:2119
>>         worker_thread+0x221/0x1850 kernel/workqueue.c:2253
>>         kthread+0x3a1/0x470 kernel/kthread.c:231
>>         ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431
>>
>> Reported-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
>> Signed-off-by: Jaejoong Kim <climbbb.kim@xxxxxxxxx>
>> ---
>>
>> Changes in v2:
>> - write a new commit message because orginal version is wrong approach
>> - add check hid descriptor size
>> - get proper value for bNumDescriptors as suggested by Alan Stern
>> - fix the Reported-by
>>
>>  drivers/hid/usbhid/hid-core.c | 12 +++++++++++-
>>  1 file changed, 11 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c
>> index 089bad8..045b5da 100644
>> --- a/drivers/hid/usbhid/hid-core.c
>> +++ b/drivers/hid/usbhid/hid-core.c
>> @@ -975,6 +975,8 @@ static int usbhid_parse(struct hid_device *hid)
>>         unsigned int rsize = 0;
>>         char *rdesc;
>>         int ret, n;
>> +       int num_descriptors;
>> +       size_t offset = offsetof(struct hid_descriptor, desc);
>>
>>         quirks = usbhid_lookup_quirk(le16_to_cpu(dev->descriptor.idVendor),
>>                         le16_to_cpu(dev->descriptor.idProduct));
>> @@ -997,10 +999,18 @@ static int usbhid_parse(struct hid_device *hid)
>>                 return -ENODEV;
>>         }
>>
>> +       if (hdesc->bLength < sizeof(struct hid_descriptor)) {
>> +               dbg_hid("hid descriptor is too short\n");
>> +               return -EINVAL;
>> +       }
>> +
>>         hid->version = le16_to_cpu(hdesc->bcdHID);
>>         hid->country = hdesc->bCountryCode;
>>
>> -       for (n = 0; n < hdesc->bNumDescriptors; n++)
>> +       num_descriptors = min_t(int, hdesc->bNumDescriptors,
>> +              (hdesc->bLength - offset) / sizeof(struct hid_class_descriptor));
>> +
>> +       for (n = 0; n < num_descriptors; n++)
>>                 if (hdesc->desc[n].bDescriptorType == HID_DT_REPORT)
>>                         rsize = le16_to_cpu(hdesc->desc[n].wDescriptorLength);
>>
>> --
>> 2.7.4
>>
>
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