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SubjectRe: usb/hid: slab-out-of-bounds read in usbhid_parse
On Tue, Sep 19, 2017 at 1:47 PM, Kim Jaejoong <climbbb.kim@gmail.com> wrote:
> Hi, Andrey Konovalov
>
> Thanks for the report.
>
> 2017-09-19 2:33 GMT+09:00 Andrey Konovalov <andreyknvl@google.com>:
>> Hi!
>>
>> I've got the following crash while fuzzing the kernel with syzkaller.
>>
>> On commit ebb2c2437d8008d46796902ff390653822af6cc4 (Sep 18).
>>
>> It seems that there's no proper check on the hdesc->bNumDescriptors
>> value in usbhid_parse(). it iterates over hdesc->desc and accesses
>> hdesc->desc[n] fields, which might be out-of-bounds.
>
> The bNumDescriptors in hid descriptor means 'numeric expression
> specifying the number of class descriptors'.
> The value bNumberDescriptors identifies the number of additional class
> specific descriptors present.
> (refer to the 6.1.2 HID Descriptor in hid documents :
> http://www.usb.org/developers/hidpage/HID1_11.pdf)
>
> So, it can be out-of-bounds in hdesc->desc[n] if there is an
> additional class descriptor.
>
> Does the patch below fix this?

Hi Kim,

I'm not sure. Is there a check on the bLength field of a
hid_descriptor struct? Can it be less than sizeof(struct
hid_descriptor)? If so, we still do an out-of-bounds access to
hdesc->desc[0] (or some other fields).

Thanks!

>
> Thanks, jaejoong
> ------
>
> diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c
> index 089bad8..7b6a0b6 100644
> --- a/drivers/hid/usbhid/hid-core.c
> +++ b/drivers/hid/usbhid/hid-core.c
> @@ -974,7 +974,7 @@ static int usbhid_parse(struct hid_device *hid)
> u32 quirks = 0;
> unsigned int rsize = 0;
> char *rdesc;
> - int ret, n;
> + int ret;
>
> quirks = usbhid_lookup_quirk(le16_to_cpu(dev->descriptor.idVendor),
> le16_to_cpu(dev->descriptor.idProduct));
> @@ -1000,9 +1000,8 @@ static int usbhid_parse(struct hid_device *hid)
> hid->version = le16_to_cpu(hdesc->bcdHID);
> hid->country = hdesc->bCountryCode;
>
> - for (n = 0; n < hdesc->bNumDescriptors; n++)
> - if (hdesc->desc[n].bDescriptorType == HID_DT_REPORT)
> - rsize = le16_to_cpu(hdesc->desc[n].wDescriptorLength);
> + if (hdesc->desc[0].bDescriptorType == HID_DT_REPORT)
> + rsize = le16_to_cpu(hdesc->desc[0].wDescriptorLength);
>
> if (!rsize || rsize > HID_MAX_DESCRIPTOR_SIZE) {
> dbg_hid("weird size of report descriptor (%u)\n", rsize);
>
>
>>
>> ==================================================================
>> 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
>>
>> Allocated by task 1261:
>> save_stack_trace+0x1b/0x20 arch/x86/kernel/stacktrace.c:59
>> save_stack+0x43/0xd0 mm/kasan/kasan.c:447
>> set_track mm/kasan/kasan.c:459
>> kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
>> __kmalloc+0x14e/0x310 mm/slub.c:3782
>> kmalloc ./include/linux/slab.h:498
>> usb_get_configuration+0x372/0x2a60 drivers/usb/core/config.c:848
>> usb_enumerate_device drivers/usb/core/hub.c:2290
>> usb_new_device+0xaae/0x1020 drivers/usb/core/hub.c:2426
>> 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
>>
>> Freed by task 2927:
>> save_stack_trace+0x1b/0x20 arch/x86/kernel/stacktrace.c:59
>> save_stack+0x43/0xd0 mm/kasan/kasan.c:447
>> set_track mm/kasan/kasan.c:459
>> kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:524
>> slab_free_hook mm/slub.c:1390
>> slab_free_freelist_hook mm/slub.c:1412
>> slab_free mm/slub.c:2988
>> kfree+0xf6/0x2f0 mm/slub.c:3919
>> free_rb_tree_fname+0x8a/0xe0 fs/ext4/dir.c:402
>> ext4_htree_free_dir_info fs/ext4/dir.c:424
>> ext4_release_dir+0x49/0x70 fs/ext4/dir.c:622
>> __fput+0x33e/0x800 fs/file_table.c:210
>> ____fput+0x1a/0x20 fs/file_table.c:244
>> task_work_run+0x1af/0x280 kernel/task_work.c:112
>> tracehook_notify_resume ./include/linux/tracehook.h:191
>> exit_to_usermode_loop+0x1e1/0x220 arch/x86/entry/common.c:162
>> prepare_exit_to_usermode arch/x86/entry/common.c:197
>> syscall_return_slowpath+0x414/0x480 arch/x86/entry/common.c:266
>> entry_SYSCALL_64_fastpath+0xc0/0xc2 arch/x86/entry/entry_64.S:238
>>
>> The buggy address belongs to the object at ffff88006c5f8ea0
>> which belongs to the cache kmalloc-64 of size 64
>> The buggy address is located 63 bytes inside of
>> 64-byte region [ffff88006c5f8ea0, ffff88006c5f8ee0)
>> The buggy address belongs to the page:
>> page:ffffea0001b17e00 count:1 mapcount:0 mapping: (null) index:0x0
>> flags: 0x100000000000100(slab)
>> raw: 0100000000000100 0000000000000000 0000000000000000 00000001002a002a
>> raw: ffffea0001a83000 0000001500000015 ffff88006c403800 0000000000000000
>> page dumped because: kasan: bad access detected
>>
>> Memory state around the buggy address:
>> ffff88006c5f8d80: fb fb fb fb fb fb fb fb fc fc fc fc 00 00 00 00
>> ffff88006c5f8e00: 00 fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>>>ffff88006c5f8e80: fc fc fc fc 00 00 00 00 00 00 00 07 fc fc fc fc
>> ^
>> ffff88006c5f8f00: fb fb fb fb fb fb fb fb fc fc fc fc fb fb fb fb
>> ffff88006c5f8f80: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc
>> ==================================================================
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