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Subject[PATCH v2] HID: usbhid: fix out-of-bounds bug
Date
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@google.com>
Signed-off-by: Jaejoong Kim <climbbb.kim@gmail.com>
---

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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