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From:   "Xu, Yanfei" <yanfei.xu@windriver.com>
Subject: Re: inconsistent lock state in sco_conn_del
To:     marcel@holtmann.org, johan.hedberg@gmail.com, davem@davemloft.net,
        kuba@kernel.org
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 > syzbot has found a reproducer for the following issue on:
 >
 > HEAD commit:    e8878ab8 Merge tag 'spi-fix-v5.9-rc4' of 
git://git.kernel...
 > git tree:       upstream
 > console output: https://syzkaller.appspot.com/x/log.txt?x=12130759900000
 > kernel config: 
https://syzkaller.appspot.com/x/.config?x=c61610091f4ca8c4
 > dashboard link: 
https://syzkaller.appspot.com/bug?extid=65684128cd7c35bc66a1
 > compiler:       gcc (GCC) 10.1.0-syz 20200507
 > syz repro: 
https://syzkaller.appspot.com/x/repro.syz?x=121ef0fd900000
 > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16c3a853900000
 >
 > IMPORTANT: if you fix the issue, please add the following tag to the 
commit:
 > Reported-by: syzbot+65684128cd7c35bc66a1@syzkaller.appspotmail.com
 >
 > ================================
 > WARNING: inconsistent lock state
 > 5.9.0-rc4-syzkaller #0 Not tainted
 > --------------------------------
 > inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage.
 > syz-executor675/31233 [HC0[0]:SC0[0]:HE1:SE1] takes:
 > ffff8880a75c50a0 (slock-AF_BLUETOOTH-BTPROTO_SCO){+.?.}-{2:2}, at: 
spin_lock include/linux/spinlock.h:354 [inline]
 > ffff8880a75c50a0 (slock-AF_BLUETOOTH-BTPROTO_SCO){+.?.}-{2:2}, at: 
sco_conn_del+0x128/0x270 net/bluetooth/sco.c:176
 > {IN-SOFTIRQ-W} state was registered at:
 >    lock_acquire+0x1f3/0xae0 kernel/locking/lockdep.c:5006
 >    __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
 >    _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
 >    spin_lock include/linux/spinlock.h:354 [inline]
 >    sco_sock_timeout+0x24/0x140 net/bluetooth/sco.c:83
 >    call_timer_fn+0x1ac/0x760 kernel/time/timer.c:1413
 >    expire_timers kernel/time/timer.c:1458 [inline]
 >    __run_timers.part.0+0x67c/0xaa0 kernel/time/timer.c:1755
 >    __run_timers kernel/time/timer.c:1736 [inline]
 >    run_timer_softirq+0xae/0x1a0 kernel/time/timer.c:1768
 >    __do_softirq+0x1f7/0xa91 kernel/softirq.c:298
 >    asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:706
 >    __run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline]
 >    run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline]
 >    do_softirq_own_stack+0x9d/0xd0 arch/x86/kernel/irq_64.c:77
 >    invoke_softirq kernel/softirq.c:393 [inline]
 >    __irq_exit_rcu kernel/softirq.c:423 [inline]
 >    irq_exit_rcu+0x235/0x280 kernel/softirq.c:435
 >    sysvec_apic_timer_interrupt+0x51/0xf0 arch/x86/kernel/apic/apic.c:1091
 >    asm_sysvec_apic_timer_interrupt+0x12/0x20 
arch/x86/include/asm/idtentry.h:581
 >    unwind_next_frame+0x139a/0x1f90 arch/x86/kernel/unwind_orc.c:607
 >    arch_stack_walk+0x81/0xf0 arch/x86/kernel/stacktrace.c:25
 >    stack_trace_save+0x8c/0xc0 kernel/stacktrace.c:123
 >    kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
 >    kasan_set_track mm/kasan/common.c:56 [inline]
 >    __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:461
 >    slab_post_alloc_hook mm/slab.h:518 [inline]
 >    slab_alloc mm/slab.c:3312 [inline]
 >    kmem_cache_alloc+0x13a/0x3a0 mm/slab.c:3482
 >    __d_alloc+0x2a/0x950 fs/dcache.c:1709
 >    d_alloc+0x4a/0x230 fs/dcache.c:1788
 >    d_alloc_parallel+0xe9/0x18e0 fs/dcache.c:2540
 >    lookup_open.isra.0+0x9ac/0x1350 fs/namei.c:3030
 >    open_last_lookups fs/namei.c:3177 [inline]
 >    path_openat+0x96d/0x2730 fs/namei.c:3365
 >    do_filp_open+0x17e/0x3c0 fs/namei.c:3395
 >    do_sys_openat2+0x16d/0x420 fs/open.c:1168
 >    do_sys_open fs/open.c:1184 [inline]
 >    __do_sys_open fs/open.c:1192 [inline]
 >    __se_sys_open fs/open.c:1188 [inline]
 >    __x64_sys_open+0x119/0x1c0 fs/open.c:1188
 >    do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 >    entry_SYSCALL_64_after_hwframe+0x44/0xa9
 > irq event stamp: 853
 > hardirqs last  enabled at (853): [<ffffffff87f733af>] 
__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:168 [inline]
 > hardirqs last  enabled at (853): [<ffffffff87f733af>] 
_raw_spin_unlock_irq+0x1f/0x80 kernel/locking/spinlock.c:199
 > hardirqs last disabled at (852): [<ffffffff87f73764>] 
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:126 [inline]
 > hardirqs last disabled at (852): [<ffffffff87f73764>] 
_raw_spin_lock_irq+0xa4/0xd0 kernel/locking/spinlock.c:167
 > softirqs last  enabled at (0): [<ffffffff8144c929>] 
copy_process+0x1a99/0x6920 kernel/fork.c:2018
 > softirqs last disabled at (0): [<0000000000000000>] 0x0
 >
 > other info that might help us debug this:
 >   Possible unsafe locking scenario:
 >
 >         CPU0
 >         ----
 >    lock(slock-AF_BLUETOOTH-BTPROTO_SCO);
 >    <Interrupt>
 >      lock(slock-AF_BLUETOOTH-BTPROTO_SCO);
 >
 >   *** DEADLOCK ***
 >
 > 3 locks held by syz-executor675/31233:
 >   #0: ffff88809f104f40 (&hdev->req_lock){+.+.}-{3:3}, at: 
hci_dev_do_close+0xf5/0x1080 net/bluetooth/hci_core.c:1720
 >   #1: ffff88809f104078 (&hdev->lock){+.+.}-{3:3}, at: 
hci_dev_do_close+0x253/0x1080 net/bluetooth/hci_core.c:1757
 >   #2: ffffffff8a9188c8 (hci_cb_list_lock){+.+.}-{3:3}, at: 
hci_disconn_cfm include/net/bluetooth/hci_core.h:1435 [inline]
 >   #2: ffffffff8a9188c8 (hci_cb_list_lock){+.+.}-{3:3}, at: 
hci_conn_hash_flush+0xc7/0x220 net/bluetooth/hci_conn.c:1557
 >
 > stack backtrace:
 > CPU: 1 PID: 31233 Comm: syz-executor675 Not tainted 
5.9.0-rc4-syzkaller #0
 > 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+0x198/0x1fd lib/dump_stack.c:118
 >   print_usage_bug kernel/locking/lockdep.c:4020 [inline]
 >   valid_state kernel/locking/lockdep.c:3361 [inline]
 >   mark_lock_irq kernel/locking/lockdep.c:3560 [inline]
 >   mark_lock.cold+0x7a/0x7f kernel/locking/lockdep.c:4006
 >   mark_usage kernel/locking/lockdep.c:3923 [inline]
 >   __lock_acquire+0x876/0x5570 kernel/locking/lockdep.c:4380
 >   lock_acquire+0x1f3/0xae0 kernel/locking/lockdep.c:5006
 >   __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
 >   _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
 >   spin_lock include/linux/spinlock.h:354 [inline]
 >   sco_conn_del+0x128/0x270 net/bluetooth/sco.c:176

Locking slock-AF_BLUETOOTH-BTPROTO_SCO may happen in process context or 
BH context. If in process context, we should use lock_sock(). 
sco_conn_del() is called in process context here, so how about using
lock_sock() instead of bh_lock_sock()

changes as:
diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c
index dcf7f96ff417..559b883c815f 100644
--- a/net/bluetooth/sco.c
+++ b/net/bluetooth/sco.c
@@ -173,10 +173,10 @@ static void sco_conn_del(struct hci_conn *hcon, 
int err)

         if (sk) {
                 sock_hold(sk);
-               bh_lock_sock(sk);
+               lock_sock(sk);
                 sco_sock_clear_timer(sk);
                 sco_chan_del(sk, err);
-               bh_unlock_sock(sk);
+               release_sock(sk);
                 sco_sock_kill(sk);
                 sock_put(sk);
         }
-- 

Regards,

Yanfei

 >   sco_disconn_cfm net/bluetooth/sco.c:1178 [inline]
 >   sco_disconn_cfm+0x62/0x80 net/bluetooth/sco.c:1171
 >   hci_disconn_cfm include/net/bluetooth/hci_core.h:1438 [inline]
 >   hci_conn_hash_flush+0x114/0x220 net/bluetooth/hci_conn.c:1557
 >   hci_dev_do_close+0x5c6/0x1080 net/bluetooth/hci_core.c:1770
 >   hci_unregister_dev+0x1bd/0xe30 net/bluetooth/hci_core.c:3790
 >   vhci_release+0x70/0xe0 drivers/bluetooth/hci_vhci.c:340
 >   __fput+0x285/0x920 fs/file_table.c:281
 >   task_work_run+0xdd/0x190 kernel/task_work.c:141
 >   exit_task_work include/linux/task_work.h:25 [inline]
 >   do_exit+0xb7d/0x29f0 kernel/exit.c:806
 >   do_group_exit+0x125/0x310 kernel/exit.c:903
 >   get_signal+0x428/0x1f00 kernel/signal.c:2757
 >   arch_do_signal+0x82/0x2520 arch/x86/kernel/signal.c:811
 >   exit_to_user_mode_loop kernel/entry/common.c:159 [inline]
 >   exit_to_user_mode_prepare+0x1ae/0x200 kernel/entry/common.c:190
 >   syscall_exit_to_user_mode+0x7e/0x2e0 kernel/entry/common.c:265
 >   entry_SYSCALL_64_after_hwframe+0x44/0xa9
 > RIP: 0033:0x447279
 > Code: Bad RIP value.
 > RSP: 002b:00007fd19f624d88 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
 > RAX: fffffffffffffe00 RBX: 00000000006dcc28 RCX: 0000000000447279
 > RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00000000006dcc28
 > RBP: 00000000006dcc20 R08: 0000000000000000 R09: 0000000000000000
 > R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dcc2c
 > R13: 0000000000000004 R14: 0000000000000003 R15: 00007fd19f6256d0
 >