KASAN: use-after-free Write in hiddev_disconnect

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 5a67532c usb: gadget: add raw-gadget interface
git tree: https://github.com/google/kasan.git usb-fuzzer
console output: https://syzkaller.appspot.com/x/log.txt?x=10b1419ee00000
kernel config: https://syzkaller.appspot.com/x/.config?x=9ba75825443d54bd
dashboard link: https://syzkaller.appspot.com/bug?extid=784ccb935f9900cc7c9e
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+784ccb...@syzkaller.appspotmail.com

usb 6-1: USB disconnect, device number 34
==================================================================
BUG: KASAN: use-after-free in register_lock_class+0xeda/0x11d0
kernel/locking/lockdep.c:1263
Write of size 8 at addr ffff8881ce6284b0 by task kworker/0:3/3833

CPU: 0 PID: 3833 Comm: kworker/0:3 Not tainted 5.5.0-rc6-syzkaller #0
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+0xef/0x16e lib/dump_stack.c:118
print_address_description.constprop.0.cold+0xd3/0x314 mm/kasan/report.c:374
__kasan_report.cold+0x37/0x85 mm/kasan/report.c:506
kasan_report+0xe/0x20 mm/kasan/common.c:639
register_lock_class+0xeda/0x11d0 kernel/locking/lockdep.c:1263
__lock_acquire+0xfc/0x3b60 kernel/locking/lockdep.c:3837
lock_acquire+0x130/0x340 kernel/locking/lockdep.c:4485
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x32/0x50 kernel/locking/spinlock.c:159
__wake_up_common_lock+0xb4/0x130 kernel/sched/wait.c:122
hiddev_disconnect+0x154/0x1b4 drivers/hid/usbhid/hiddev.c:937
hid_disconnect+0xb4/0x1a0 drivers/hid/hid-core.c:2008
hid_hw_stop+0x12/0x70 drivers/hid/hid-core.c:2053
cmhid_remove+0x38/0x50 drivers/hid/hid-cmedia.c:140
hid_device_remove+0xed/0x240 drivers/hid/hid-core.c:2294
__device_release_driver drivers/base/dd.c:1132 [inline]
device_release_driver_internal+0x231/0x500 drivers/base/dd.c:1165
bus_remove_device+0x2eb/0x5a0 drivers/base/bus.c:532
device_del+0x481/0xd30 drivers/base/core.c:2664
hid_remove_device drivers/hid/hid-core.c:2465 [inline]
hid_destroy_device+0xe1/0x150 drivers/hid/hid-core.c:2484
usbhid_disconnect+0x9f/0xe0 drivers/hid/usbhid/hid-core.c:1413
usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:423
__device_release_driver drivers/base/dd.c:1134 [inline]
device_release_driver_internal+0x42f/0x500 drivers/base/dd.c:1165
bus_remove_device+0x2eb/0x5a0 drivers/base/bus.c:532
device_del+0x481/0xd30 drivers/base/core.c:2664
usb_disable_device+0x23d/0x790 drivers/usb/core/message.c:1237
usb_disconnect+0x293/0x900 drivers/usb/core/hub.c:2200
hub_port_connect drivers/usb/core/hub.c:5035 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5324 [inline]
port_event drivers/usb/core/hub.c:5470 [inline]
hub_event+0x1a1d/0x4300 drivers/usb/core/hub.c:5552
process_one_work+0x945/0x15c0 kernel/workqueue.c:2264
worker_thread+0x96/0xe20 kernel/workqueue.c:2410
kthread+0x318/0x420 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Allocated by task 5:
save_stack+0x1b/0x80 mm/kasan/common.c:72
set_track mm/kasan/common.c:80 [inline]
__kasan_kmalloc mm/kasan/common.c:513 [inline]
__kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:486
kmalloc include/linux/slab.h:556 [inline]
kzalloc include/linux/slab.h:670 [inline]
hiddev_connect+0x242/0x5b0 drivers/hid/usbhid/hiddev.c:890
hid_connect+0x239/0xbb0 drivers/hid/hid-core.c:1934
hid_hw_start drivers/hid/hid-core.c:2033 [inline]
hid_hw_start+0xa2/0x130 drivers/hid/hid-core.c:2024
cmhid_probe+0x104/0x160 drivers/hid/hid-cmedia.c:123
hid_device_probe+0x2be/0x3f0 drivers/hid/hid-core.c:2261
really_probe+0x290/0xad0 drivers/base/dd.c:548
driver_probe_device+0x223/0x350 drivers/base/dd.c:721
__device_attach_driver+0x1d1/0x290 drivers/base/dd.c:828
bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:430
__device_attach+0x217/0x390 drivers/base/dd.c:894
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:490
device_add+0x1459/0x1bf0 drivers/base/core.c:2487
hid_add_device drivers/hid/hid-core.c:2417 [inline]
hid_add_device+0x33c/0x9a0 drivers/hid/hid-core.c:2366
usbhid_probe+0xa81/0xfa0 drivers/hid/usbhid/hid-core.c:1386
usb_probe_interface+0x310/0x800 drivers/usb/core/driver.c:361
really_probe+0x290/0xad0 drivers/base/dd.c:548
driver_probe_device+0x223/0x350 drivers/base/dd.c:721
__device_attach_driver+0x1d1/0x290 drivers/base/dd.c:828
bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:430
__device_attach+0x217/0x390 drivers/base/dd.c:894
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:490
device_add+0x1459/0x1bf0 drivers/base/core.c:2487
usb_set_configuration+0xe47/0x17d0 drivers/usb/core/message.c:2023
generic_probe+0x9d/0xd5 drivers/usb/core/generic.c:210
usb_probe_device+0xaf/0x140 drivers/usb/core/driver.c:266
really_probe+0x290/0xad0 drivers/base/dd.c:548
driver_probe_device+0x223/0x350 drivers/base/dd.c:721
__device_attach_driver+0x1d1/0x290 drivers/base/dd.c:828
bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:430
__device_attach+0x217/0x390 drivers/base/dd.c:894
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:490
device_add+0x1459/0x1bf0 drivers/base/core.c:2487
usb_new_device.cold+0x540/0xcd0 drivers/usb/core/hub.c:2537
hub_port_connect drivers/usb/core/hub.c:5184 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5324 [inline]
port_event drivers/usb/core/hub.c:5470 [inline]
hub_event+0x21cb/0x4300 drivers/usb/core/hub.c:5552
process_one_work+0x945/0x15c0 kernel/workqueue.c:2264
worker_thread+0x96/0xe20 kernel/workqueue.c:2410
kthread+0x318/0x420 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Freed by task 4638:
save_stack+0x1b/0x80 mm/kasan/common.c:72
set_track mm/kasan/common.c:80 [inline]
kasan_set_free_info mm/kasan/common.c:335 [inline]
__kasan_slab_free+0x117/0x160 mm/kasan/common.c:474
slab_free_hook mm/slub.c:1425 [inline]
slab_free_freelist_hook mm/slub.c:1458 [inline]
slab_free mm/slub.c:3005 [inline]
kfree+0xd5/0x300 mm/slub.c:3957
hiddev_release+0x402/0x520 drivers/hid/usbhid/hiddev.c:232
__fput+0x2d7/0x840 fs/file_table.c:280
task_work_run+0x13f/0x1c0 kernel/task_work.c:113
exit_task_work include/linux/task_work.h:22 [inline]
do_exit+0xb8b/0x2c50 kernel/exit.c:801
do_group_exit+0x125/0x340 kernel/exit.c:899
get_signal+0x480/0x2470 kernel/signal.c:2734
do_signal+0x88/0x1490 arch/x86/kernel/signal.c:815
exit_to_usermode_loop+0x1a2/0x200 arch/x86/entry/common.c:160
prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
syscall_return_slowpath arch/x86/entry/common.c:278 [inline]
do_syscall_64+0x4e0/0x5a0 arch/x86/entry/common.c:304
entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8881ce628400
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 176 bytes inside of
512-byte region [ffff8881ce628400, ffff8881ce628600)
The buggy address belongs to the page:
page:ffffea0007398a00 refcount:1 mapcount:0 mapping:ffff8881da002500
index:0xffff8881ce62a800 compound_mapcount: 0
raw: 0200000000010200 0000000000000000 0000000100000001 ffff8881da002500
raw: ffff8881ce62a800 000000008010000f 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8881ce628380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8881ce628400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8881ce628480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8881ce628500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8881ce628580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
This bug is generated by a bot. It may contain errors.
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[Dan Carpenter]

I'm trying to take a stab at diagnosing these bugs. (But I'm seldom
smart enough to actually fix anything). These hiddev_disconnect() bugs
are a race condition:

devel/drivers/hid/usbhid/hiddev.c
924 void hiddev_disconnect(struct hid_device *hid)
925 {
926 struct hiddev *hiddev = hid->hiddev;
927 struct usbhid_device *usbhid = hid->driver_data;
928
929 usb_deregister_dev(usbhid->intf, &hiddev_class);
930
931 mutex_lock(&hiddev->existancelock);
932 hiddev->exist = 0;
^^^^^^^^^^^^^^^^^^
We set "exist = 0;"

933
934 if (hiddev->open) {
935 mutex_unlock(&hiddev->existancelock);
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Then we drop the lock.

936 hid_hw_close(hiddev->hid);
937 wake_up_interruptible(&hiddev->wait);
^^^^^^
The other thread frees hiddev and it crashes here.

938 } else {
939 mutex_unlock(&hiddev->existancelock);
940 kfree(hiddev);
941 }
942 }

The other thread is doing:

drivers/hid/usbhid/hiddev.c
216 static int hiddev_release(struct inode * inode, struct file * file)
217 {
218 struct hiddev_list *list = file->private_data;
219 unsigned long flags;
220
221 spin_lock_irqsave(&list->hiddev->list_lock, flags);
222 list_del(&list->node);
223 spin_unlock_irqrestore(&list->hiddev->list_lock, flags);
224
225 mutex_lock(&list->hiddev->existancelock);
^^^^^^^^^^^^^^^^^^^^^^^^^^^
Takes the lock.

226 if (!--list->hiddev->open) {
^^^^^^^^^^^^^^^^^^^^
Decrements open.

227 if (list->hiddev->exist) {
^^^^^^^^^^^^^^^^^^^
This is false.

228 hid_hw_close(list->hiddev->hid);
229 hid_hw_power(list->hiddev->hid, PM_HINT_NORMAL);
230 } else {
231 mutex_unlock(&list->hiddev->existancelock);
232 kfree(list->hiddev);
^^^^^^^^^^^^
Freed here.

233 vfree(list);
234 return 0;
235 }
236 }
237
238 mutex_unlock(&list->hiddev->existancelock);
239 vfree(list);
240
241 return 0;
242 }

I'm not sure what the fix should be though.

regards,
dan carpenter

[Alan Stern]

Good sleuthing!

It certainly looks as though hiddev_disconnect() should not try to
reference hiddev after dropping the existance_lock -- at least, not in
the case that the device file is still open. So I suggest reordering
the statements in that routine: First call hid_hw_close() and
wake_up_interruptible(), then drop the mutex.

Too bad syzbot doesn't have a reproducer to test this, though.

Alan Stern