syzbot

audit: type=1400 audit(1571664420.365:37): avc:  denied  { map } for  pid=7053 comm="syz-executor788" path="/dev/usbmon0" dev="devtmpfs" ino=14731 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=system_u:object_r:usbmon_device_t:s0 tclass=chr_file permissive=1
======================================================
WARNING: possible circular locking dependency detected
4.14.150 #0 Not tainted
------------------------------------------------------
syz-executor788/7064 is trying to acquire lock:
 (&mm->mmap_sem){++++}, at: [<ffffffff817c00b0>] __might_fault+0xe0/0x1d0 mm/memory.c:4583

but task is already holding lock:
 (&rp->fetch_lock){+.+.}, at: [<ffffffff83f77c97>] mon_bin_fetch+0x37/0x2e0 drivers/usb/mon/mon_bin.c:909

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&rp->fetch_lock){+.+.}:
       lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994
       __mutex_lock_common kernel/locking/mutex.c:756 [inline]
       __mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893
       mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
       mon_bin_vma_fault+0x6f/0x280 drivers/usb/mon/mon_bin.c:1236
       __do_fault+0x104/0x390 mm/memory.c:3223
       do_cow_fault mm/memory.c:3662 [inline]
       do_fault mm/memory.c:3761 [inline]
       handle_pte_fault mm/memory.c:3989 [inline]
       __handle_mm_fault+0xde1/0x3470 mm/memory.c:4113
       handle_mm_fault+0x293/0x7c0 mm/memory.c:4150
       __do_page_fault+0x4c1/0xb80 arch/x86/mm/fault.c:1420
       do_page_fault+0x71/0x511 arch/x86/mm/fault.c:1495
       page_fault+0x45/0x50 arch/x86/entry/entry_64.S:1122

-> #0 (&mm->mmap_sem){++++}:
       check_prev_add kernel/locking/lockdep.c:1901 [inline]
       check_prevs_add kernel/locking/lockdep.c:2018 [inline]
       validate_chain kernel/locking/lockdep.c:2460 [inline]
       __lock_acquire+0x2cb3/0x4620 kernel/locking/lockdep.c:3487
       lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994
       __might_fault mm/memory.c:4584 [inline]
       __might_fault+0x143/0x1d0 mm/memory.c:4569
       mon_bin_fetch+0x212/0x2e0 drivers/usb/mon/mon_bin.c:928
       mon_bin_ioctl+0x1c5/0xb50 drivers/usb/mon/mon_bin.c:1090
       vfs_ioctl fs/ioctl.c:46 [inline]
       file_ioctl fs/ioctl.c:500 [inline]
       do_vfs_ioctl+0x7ae/0x1060 fs/ioctl.c:684
       SYSC_ioctl fs/ioctl.c:701 [inline]
       SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
       do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
       entry_SYSCALL_64_after_hwframe+0x42/0xb7

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&rp->fetch_lock);
                               lock(&mm->mmap_sem);
                               lock(&rp->fetch_lock);
  lock(&mm->mmap_sem);

 *** DEADLOCK ***

1 lock held by syz-executor788/7064:
 #0:  (&rp->fetch_lock){+.+.}, at: [<ffffffff83f77c97>] mon_bin_fetch+0x37/0x2e0 drivers/usb/mon/mon_bin.c:909

stack backtrace:
CPU: 1 PID: 7064 Comm: syz-executor788 Not tainted 4.14.150 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x138/0x197 lib/dump_stack.c:53
 print_circular_bug.isra.0.cold+0x1cc/0x28f kernel/locking/lockdep.c:1258
 check_prev_add kernel/locking/lockdep.c:1901 [inline]
 check_prevs_add kernel/locking/lockdep.c:2018 [inline]
 validate_chain kernel/locking/lockdep.c:2460 [inline]
 __lock_acquire+0x2cb3/0x4620 kernel/locking/lockdep.c:3487
 lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994
 __might_fault mm/memory.c:4584 [inline]
 __might_fault+0x143/0x1d0 mm/memory.c:4569
 mon_bin_fetch+0x212/0x2e0 drivers/usb/mon/mon_bin.c:928
 mon_bin_ioctl+0x1c5/0xb50 drivers/usb/mon/mon_bin.c:1090
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x7ae/0x1060 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x44b0a9
RSP: 002b:00007f09f146fce8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000006ddc38 RCX: 000000000044b0a9
RDX: 0000000020000140 RSI: 00000000c0109207 RDI: 0000000000000003
RBP: 00000000006ddc30 R08: 00007f09f1470700 R09: 0000000000000000
R10: 00007f09f1470700 R11: 0000000000000246 R12: 00000000006ddc3c
R13: 00007ffe757f2fef R14: 00007f09f14709c0 R15: 000000000000002d
IPv6: ADDRCONF(NETDEV_CHANGE): bond0: link becomes ready
syz-executor788 (7053) used greatest stack depth: 24624 bytes left