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Date:   Thu, 01 Aug 2019 08:28:08 -0700
Message-ID: <00000000000088af91058f0fe377@google.com>
Subject: possible deadlock in open_rio
From:   syzbot <syzbot+7bbcbe9c9ff0cd49592a@syzkaller.appspotmail.com>
To:     andreyknvl@google.com, gregkh@linuxfoundation.org,
        linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org,
        miquel@df.uba.ar, rio500-users@lists.sourceforge.net,
        syzkaller-bugs@googlegroups.com
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Sender: linux-kernel-owner@vger.kernel.org
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Hello,

syzbot found the following crash on:

HEAD commit:    7f7867ff 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=136b6aec600000
kernel config:  https://syzkaller.appspot.com/x/.config?x=792eb47789f57810
dashboard link: https://syzkaller.appspot.com/bug?extid=7bbcbe9c9ff0cd49592a
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+7bbcbe9c9ff0cd49592a@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
5.3.0-rc2+ #23 Not tainted
------------------------------------------------------
syz-executor.2/20386 is trying to acquire lock:
00000000772249c6 (rio500_mutex){+.+.}, at: open_rio+0x16/0xc0  
drivers/usb/misc/rio500.c:64

but task is already holding lock:
00000000d3e8f4b9 (minor_rwsem){++++}, at: usb_open+0x23/0x270  
drivers/usb/core/file.c:39

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (minor_rwsem){++++}:
        down_write+0x92/0x150 kernel/locking/rwsem.c:1500
        usb_register_dev drivers/usb/core/file.c:187 [inline]
        usb_register_dev+0x131/0x6a0 drivers/usb/core/file.c:156
        probe_rio.cold+0x53/0x21d drivers/usb/misc/rio500.c:468
        usb_probe_interface+0x305/0x7a0 drivers/usb/core/driver.c:361
        really_probe+0x281/0x650 drivers/base/dd.c:548
        driver_probe_device+0x101/0x1b0 drivers/base/dd.c:709
        __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:816
        bus_for_each_drv+0x15c/0x1e0 drivers/base/bus.c:454
        __device_attach+0x217/0x360 drivers/base/dd.c:882
        bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
        device_add+0xae6/0x16f0 drivers/base/core.c:2114
        usb_set_configuration+0xdf6/0x1670 drivers/usb/core/message.c:2023
        generic_probe+0x9d/0xd5 drivers/usb/core/generic.c:210
        usb_probe_device+0x99/0x100 drivers/usb/core/driver.c:266
        really_probe+0x281/0x650 drivers/base/dd.c:548
        driver_probe_device+0x101/0x1b0 drivers/base/dd.c:709
        __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:816
        bus_for_each_drv+0x15c/0x1e0 drivers/base/bus.c:454
        __device_attach+0x217/0x360 drivers/base/dd.c:882
        bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
        device_add+0xae6/0x16f0 drivers/base/core.c:2114
        usb_new_device.cold+0x6a4/0xe79 drivers/usb/core/hub.c:2536
        hub_port_connect drivers/usb/core/hub.c:5098 [inline]
        hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
        port_event drivers/usb/core/hub.c:5359 [inline]
        hub_event+0x1b5c/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

-> #0 (rio500_mutex){+.+.}:
        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
        __mutex_lock_common kernel/locking/mutex.c:930 [inline]
        __mutex_lock+0x158/0x1360 kernel/locking/mutex.c:1077
        open_rio+0x16/0xc0 drivers/usb/misc/rio500.c:64
        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

other info that might help us debug this:

  Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(minor_rwsem);
                                lock(rio500_mutex);
                                lock(minor_rwsem);
   lock(rio500_mutex);

  *** DEADLOCK ***

1 lock held by syz-executor.2/20386:
  #0: 00000000d3e8f4b9 (minor_rwsem){++++}, at: usb_open+0x23/0x270  
drivers/usb/core/file.c:39

stack backtrace:
CPU: 1 PID: 20386 Comm: syz-executor.2 Not tainted 5.3.0-rc2+ #23
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
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
  __mutex_lock_common kernel/locking/mutex.c:930 [inline]
  __mutex_lock+0x158/0x1360 kernel/locking/mutex.c:1077
  open_rio+0x16/0xc0 drivers/usb/misc/rio500.c:64
  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
RIP: 0033:0x413711
Code: 75 14 b8 02 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 04 19 00 00 c3 48  
83 ec 08 e8 0a fa ff ff 48 89 04 24 b8 02 00 00 00 0f 05 <48> 8b 3c 24 48  
89 c2 e8 53 fa ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007f26383357a0 EFLAGS: 00000293 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 6666666666666667 RCX: 0000000000413711
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00007f2638335850
RBP: 000000000075bf20 R08: 000000000000000f R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000293 R12: 00007f26383366d4
R13: 00000000004c8bee R14: 00000000004dfa68 R15: 00000000ffffffff
usb 5-1: Rio opened.


---
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