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Date:   Fri, 09 Aug 2019 11:18:06 -0700
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Subject: Re: possible deadlock in usb_deregister_dev
From:   syzbot <syzbot+a64a382964bf6c71a9c0@syzkaller.appspotmail.com>
To:     andreyknvl@google.com, gregkh@linuxfoundation.org,
        linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org,
        oneukum@suse.de, syzkaller-bugs@googlegroups.com
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Sender: linux-kernel-owner@vger.kernel.org
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syzbot has found a reproducer for the following crash on:

HEAD commit:    e96407b4 usb-fuzzer: main usb gadget fuzzer driver
git tree:       https://github.com/google/kasan.git usb-fuzzer
console output: https://syzkaller.appspot.com/x/log.txt?x=15bf780e600000
kernel config:  https://syzkaller.appspot.com/x/.config?x=cfa2c18fb6a8068e
dashboard link: https://syzkaller.appspot.com/bug?extid=a64a382964bf6c71a9c0
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=16787574600000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=136cc4d2600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+a64a382964bf6c71a9c0@syzkaller.appspotmail.com

usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 1-1: config 0 descriptor??
iowarrior 1-1:0.236: IOWarrior product=0x1501, serial= interface=236 now  
attached to iowarrior0
usb 1-1: USB disconnect, device number 2
======================================================
WARNING: possible circular locking dependency detected
5.3.0-rc2+ #25 Not tainted
------------------------------------------------------
kworker/0:1/12 is trying to acquire lock:
00000000cd63e8f1 (minor_rwsem){++++}, at: usb_deregister_dev  
drivers/usb/core/file.c:238 [inline]
00000000cd63e8f1 (minor_rwsem){++++}, at: usb_deregister_dev+0x61/0x270  
drivers/usb/core/file.c:230

but task is already holding lock:
000000001d1989ef (iowarrior_open_disc_lock){+.+.}, at:  
iowarrior_disconnect+0x45/0x2c0 drivers/usb/misc/iowarrior.c:867

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (iowarrior_open_disc_lock){+.+.}:
        __mutex_lock_common kernel/locking/mutex.c:930 [inline]
        __mutex_lock+0x158/0x1360 kernel/locking/mutex.c:1077
        iowarrior_open+0x8a/0x2a0 drivers/usb/misc/iowarrior.c:600
        usb_open+0x1df/0x270 drivers/usb/core/file.c:48
        chrdev_open+0x219/0x5c0 fs/char_dev.c:414
        do_dentry_open+0x494/0x1120 fs/open.c:797
        do_last fs/namei.c:3416 [inline]
        path_openat+0x1430/0x3f50 fs/namei.c:3533
        do_filp_open+0x1a1/0x280 fs/namei.c:3563
        do_sys_open+0x3c0/0x580 fs/open.c:1089
        do_syscall_64+0xb7/0x580 arch/x86/entry/common.c:296
        entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #1 (iowarrior_mutex){+.+.}:
        __mutex_lock_common kernel/locking/mutex.c:930 [inline]
        __mutex_lock+0x158/0x1360 kernel/locking/mutex.c:1077
        iowarrior_open+0x23/0x2a0 drivers/usb/misc/iowarrior.c:589
        usb_open+0x1df/0x270 drivers/usb/core/file.c:48
        chrdev_open+0x219/0x5c0 fs/char_dev.c:414
        do_dentry_open+0x494/0x1120 fs/open.c:797
        do_last fs/namei.c:3416 [inline]
        path_openat+0x1430/0x3f50 fs/namei.c:3533
        do_filp_open+0x1a1/0x280 fs/namei.c:3563
        do_sys_open+0x3c0/0x580 fs/open.c:1089
        do_syscall_64+0xb7/0x580 arch/x86/entry/common.c:296
        entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #0 (minor_rwsem){++++}:
        check_prev_add kernel/locking/lockdep.c:2405 [inline]
        check_prevs_add kernel/locking/lockdep.c:2507 [inline]
        validate_chain kernel/locking/lockdep.c:2897 [inline]
        __lock_acquire+0x1f7c/0x3b50 kernel/locking/lockdep.c:3880
        lock_acquire+0x127/0x320 kernel/locking/lockdep.c:4412
        down_write+0x92/0x150 kernel/locking/rwsem.c:1500
        usb_deregister_dev drivers/usb/core/file.c:238 [inline]
        usb_deregister_dev+0x61/0x270 drivers/usb/core/file.c:230
        iowarrior_disconnect+0xa8/0x2c0 drivers/usb/misc/iowarrior.c:873
        usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:423
        __device_release_driver drivers/base/dd.c:1120 [inline]
        device_release_driver_internal+0x404/0x4c0 drivers/base/dd.c:1151
        bus_remove_device+0x2dc/0x4a0 drivers/base/bus.c:556
        device_del+0x420/0xb10 drivers/base/core.c:2288
        usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1237
        usb_disconnect+0x284/0x8d0 drivers/usb/core/hub.c:2199
        hub_port_connect drivers/usb/core/hub.c:4949 [inline]
        hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
        port_event drivers/usb/core/hub.c:5359 [inline]
        hub_event+0x1454/0x3640 drivers/usb/core/hub.c:5441
        process_one_work+0x92b/0x1530 kernel/workqueue.c:2269
        worker_thread+0x96/0xe20 kernel/workqueue.c:2415
        kthread+0x318/0x420 kernel/kthread.c:255
        ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

other info that might help us debug this:

Chain exists of:
   minor_rwsem --> iowarrior_mutex --> iowarrior_open_disc_lock

  Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(iowarrior_open_disc_lock);
                                lock(iowarrior_mutex);
                                lock(iowarrior_open_disc_lock);
   lock(minor_rwsem);

  *** DEADLOCK ***

6 locks held by kworker/0:1/12:
  #0: 0000000016a35280 ((wq_completion)usb_hub_wq){+.+.}, at:  
__write_once_size include/linux/compiler.h:226 [inline]
  #0: 0000000016a35280 ((wq_completion)usb_hub_wq){+.+.}, at:  
arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
  #0: 0000000016a35280 ((wq_completion)usb_hub_wq){+.+.}, at: atomic64_set  
include/asm-generic/atomic-instrumented.h:855 [inline]
  #0: 0000000016a35280 ((wq_completion)usb_hub_wq){+.+.}, at:  
atomic_long_set include/asm-generic/atomic-long.h:40 [inline]
  #0: 0000000016a35280 ((wq_completion)usb_hub_wq){+.+.}, at: set_work_data  
kernel/workqueue.c:620 [inline]
  #0: 0000000016a35280 ((wq_completion)usb_hub_wq){+.+.}, at:  
set_work_pool_and_clear_pending kernel/workqueue.c:647 [inline]
  #0: 0000000016a35280 ((wq_completion)usb_hub_wq){+.+.}, at:  
process_one_work+0x827/0x1530 kernel/workqueue.c:2240
  #1: 0000000001908f5f ((work_completion)(&hub->events)){+.+.}, at:  
process_one_work+0x85b/0x1530 kernel/workqueue.c:2244
  #2: 00000000894e02c9 (&dev->mutex){....}, at: device_lock  
include/linux/device.h:1220 [inline]
  #2: 00000000894e02c9 (&dev->mutex){....}, at: hub_event+0x17c/0x3640  
drivers/usb/core/hub.c:5387
  #3: 00000000e2dd0256 (&dev->mutex){....}, at: device_lock  
include/linux/device.h:1220 [inline]
  #3: 00000000e2dd0256 (&dev->mutex){....}, at: usb_disconnect+0x91/0x8d0  
drivers/usb/core/hub.c:2190
  #4: 0000000021bbb80a (&dev->mutex){....}, at:  
device_release_driver_internal+0x23/0x4c0 drivers/base/dd.c:1148
  #5: 000000001d1989ef (iowarrior_open_disc_lock){+.+.}, at:  
iowarrior_disconnect+0x45/0x2c0 drivers/usb/misc/iowarrior.c:867

stack backtrace:
CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.3.0-rc2+ #25
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+0xca/0x13e lib/dump_stack.c:113
  check_noncircular+0x345/0x3e0 kernel/locking/lockdep.c:1741
  check_prev_add kernel/locking/lockdep.c:2405 [inline]
  check_prevs_add kernel/locking/lockdep.c:2507 [inline]
  validate_chain kernel/locking/lockdep.c:2897 [inline]
  __lock_acquire+0x1f7c/0x3b50 kernel/locking/lockdep.c:3880
  lock_acquire+0x127/0x320 kernel/locking/lockdep.c:4412
  down_write+0x92/0x150 kernel/locking/rwsem.c:1500
  usb_deregister_dev drivers/usb/core/file.c:238 [inline]
  usb_deregister_dev+0x61/0x270 drivers/usb/core/file.c:230
  iowarrior_disconnect+0xa8/0x2c0 drivers/usb/misc/iowarrior.c:873
  usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:423
  __device_release_driver drivers/base/dd.c:1120 [inline]
  device_release_driver_internal+0x404/0x4c0 drivers/base/dd.c:1151
  bus_remove_device+0x2dc/0x4a0 drivers/base/bus.c:556
  device_del+0x420/0xb10 drivers/base/core.c:2288
  usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1237
  usb_disconnect+0x284/0x8d0 drivers/usb/core/hub.c:2199
  hub_port_connect drivers/usb/core/hub.c:4949 [inline]
  hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
  port_event drivers/usb/core/hub.c:5359 [inline]
  hub_event+0x1454/0x3640 drivers/usb/core/hub.c:5441
  process_one_work+0x92b/0x1530 kernel/workqueue.c:2269
  worker_thread+0x96/0xe20 kernel/workqueue.c:2415
  kthread+0x318/0x420 kernel/kthread.c:255
  ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
iowarrior 1-1:0.236: I/O-Warror #0 now disconnected
usb 1-1: new low-speed USB device number 3 using dummy_hcd
usb 1-1: config 0 has an invalid interface number: 236 but max is 0
usb 1-1: config 0 has an invalid descriptor of length 0, skipping remainder  
of the config
usb 1-1: config 0 has no interface number 0
usb 1-1: config 0 interface 236 altsetting 0 endpoint 0x81 is Bulk;  
changing to Interrupt
usb 1-1: New USB device found, idVendor=07c0, idProduct=1501,  
bcdDevice=74.a0
usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 1-1: config 0 descriptor??
iowarrior 1-1:0.236: IOWarrior product=0x1501, serial= interface=236 now  
attached to iowarrior0
usb 1-1: USB disconnect, device number 5
iowarrior 1-1:0.236: I/O-Warror #0 now disconnected
usb 1-1: new low-speed USB device number 6 using dummy_hcd
usb 1-1: config 0 has an invalid interface number: 236 but max is 0
usb 1-1: config 0 has an invalid descriptor of length 0, skipping remainder  
of the config
usb 1-1: config 0 has no interface number 0
usb 1-1: config 0 interface 236 altsetting 0 endpoint 0x81 is Bulk;  
changing to Interrupt
usb 1-1: New USB device found, idVendor=07c0, idProduct=1501,  
bcdDevice=74.a0
usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 1-1: config 0 descriptor??
iowarrior 1-1:0.236: IOWarrior product=0x1501, serial= interface=236 now  
attached to iowarrior0
usb 1-1: USB disconnect, device number 7
iowarrior 1-1:0.236: I/O-Warror #0 now disconnected
usb 1-1: new low-speed USB device number 8 using dummy_hcd
usb 1-1: config 0 has an invalid interface number: 236 but max is 0
usb 1-1: config 0 has an invalid descriptor of length 0, skipping remainder  
of the config
usb 1-1: config 0 has no interface number 0
usb 1-1: config 0 interface 236 altsetting 0 endpoint 0x81 is Bulk;  
changing to Interrupt
usb 1-1: New USB device found, idVendor=07c0, idProduct=1501,  
bcdDevice=74.a0
usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 1-1: config 0 descriptor??
iowarrior 1-1:0.236: IOWarrior product=0x1501, serial= interface=236 now  
attached to iowarrior0
usb 1-1: USB disconnect, device number 8
iowarrior 1-1:0.236: I/O-Warror #0 now disconnected
usb 1-1: new low-speed USB device number 9 using dummy_hcd
usb 1-1: config 0 has an invalid interface number: 236 but max is 0
usb 1-1: config 0 has an invalid descriptor of length 0, skipping remainder  
of the config
usb 1-1: config 0 has no interface number 0
usb 1-1: config 0 interface 236 altsetting 0 endpoint 0x81 is Bulk;  
changing to Interrupt
usb 1-1: New USB device found, idVendor=07c0, idProduct=1501,  
bcdDevice=74.a0
usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 1-1: config 0 descriptor??
iowarrior 1-1:0.236: IOWarrior product=0x1501, serial= interface=236 now  
attached to iowarrior0
usb 1-1: USB disconnect, device number 9
iowarrior 1-1:0.236: I/O-Warror #0 now disconnected
usb 1-1: new low-speed USB device number 10 using dummy_hcd
usb 1-1: config 0 has an invalid interface number: 236 but max is 0
usb 1-1: config 0 has an invalid descriptor of length 0, skipping remainder  
of the config
usb 1-1: config 0 has no interface number 0
usb 1-1: config 0 interface 236 altsetting 0 endpoint 0x81 is Bulk;  
changing to Interrupt
usb 1-1: New USB device found, idVendor=07c0, idProduct=1501,  
bcdDevice=74.a0
usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 1-1: config 0 descriptor??
iowarrior 1-1:0.236: IOWarrior product=0x1501, serial= interface=236 now  
attached to iowarrior0
usb 1-1: USB disconnect, device number 11
iowarrior 1-1:0.236: I/O-Warror #0 now disconnected