Hello, syzbot found the following issue on: HEAD commit: a3fa7a101dcf Merge branches 'akpm' and 'akpm-hotfixes' (pa.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=10d61a8b300000 kernel config: https://syzkaller.appspot.com/x/.config?x=a9b60f3b657f313d dashboard link: https://syzkaller.appspot.com/bug?extid=d7ce59b06b3eb14fd218 compiler: Debian clang version 11.0.1-2, GNU ld (GNU Binutils for Debian) 2.35.1 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15247a7d300000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12a2642b300000 The issue was bisected to: commit 1804fdf6e494e5e2938c65d8391690b59bcff897 Author: Tedd Ho-Jeong An <tedd.an@xxxxxxxxx> Date: Thu Aug 5 00:32:19 2021 +0000 Bluetooth: btintel: Combine setting up MSFT extension bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=125f4163300000 final oops: https://syzkaller.appspot.com/x/report.txt?x=115f4163300000 console output: https://syzkaller.appspot.com/x/log.txt?x=165f4163300000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+d7ce59b06b3eb14fd218@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: 1804fdf6e494 ("Bluetooth: btintel: Combine setting up MSFT extension") ====================================================== WARNING: possible circular locking dependency detected 5.14.0-syzkaller #0 Not tainted ------------------------------------------------------ krfcommd/2875 is trying to acquire lock: ffff888012b9d120 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1612 [inline] ffff888012b9d120 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: rfcomm_sk_state_change+0x63/0x300 net/bluetooth/rfcomm/sock.c:73 but task is already holding lock: ffff88807cf12528 (&d->lock){+.+.}-{3:3}, at: __rfcomm_dlc_close+0x281/0x480 net/bluetooth/rfcomm/core.c:487 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&d->lock){+.+.}-{3:3}: lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5625 __mutex_lock_common+0x1df/0x2550 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:743 __rfcomm_dlc_close+0x281/0x480 net/bluetooth/rfcomm/core.c:487 rfcomm_process_dlcs+0x92/0x620 net/bluetooth/rfcomm/core.c:1844 rfcomm_process_sessions+0x2f6/0x3f0 net/bluetooth/rfcomm/core.c:2003 rfcomm_run+0x195/0x2c0 net/bluetooth/rfcomm/core.c:2086 kthread+0x453/0x480 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 -> #1 (rfcomm_mutex){+.+.}-{3:3}: lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5625 __mutex_lock_common+0x1df/0x2550 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:743 rfcomm_dlc_open+0x25/0x50 net/bluetooth/rfcomm/core.c:425 rfcomm_sock_connect+0x285/0x470 net/bluetooth/rfcomm/sock.c:413 __sys_connect_file net/socket.c:1896 [inline] __sys_connect+0x38a/0x410 net/socket.c:1913 __do_sys_connect net/socket.c:1923 [inline] __se_sys_connect net/socket.c:1920 [inline] __x64_sys_connect+0x76/0x80 net/socket.c:1920 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #0 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}: check_prev_add kernel/locking/lockdep.c:3051 [inline] check_prevs_add kernel/locking/lockdep.c:3174 [inline] validate_chain+0x1dfb/0x8240 kernel/locking/lockdep.c:3789 __lock_acquire+0x1382/0x2b00 kernel/locking/lockdep.c:5015 lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5625 lock_sock_nested+0xc6/0x110 net/core/sock.c:3191 lock_sock include/net/sock.h:1612 [inline] rfcomm_sk_state_change+0x63/0x300 net/bluetooth/rfcomm/sock.c:73 __rfcomm_dlc_close+0x2cc/0x480 net/bluetooth/rfcomm/core.c:489 rfcomm_process_dlcs+0x92/0x620 net/bluetooth/rfcomm/core.c:1844 rfcomm_process_sessions+0x2f6/0x3f0 net/bluetooth/rfcomm/core.c:2003 rfcomm_run+0x195/0x2c0 net/bluetooth/rfcomm/core.c:2086 kthread+0x453/0x480 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 other info that might help us debug this: Chain exists of: sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM --> rfcomm_mutex --> &d->lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&d->lock); lock(rfcomm_mutex); lock(&d->lock); lock(sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM); *** DEADLOCK *** 2 locks held by krfcommd/2875: #0: ffffffff8dac7488 (rfcomm_mutex){+.+.}-{3:3}, at: rfcomm_process_sessions+0x21/0x3f0 net/bluetooth/rfcomm/core.c:1979 #1: ffff88807cf12528 (&d->lock){+.+.}-{3:3}, at: __rfcomm_dlc_close+0x281/0x480 net/bluetooth/rfcomm/core.c:487 stack backtrace: CPU: 1 PID: 2875 Comm: krfcommd Not tainted 5.14.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1dc/0x2d8 lib/dump_stack.c:106 check_noncircular+0x2f9/0x3b0 kernel/locking/lockdep.c:2131 check_prev_add kernel/locking/lockdep.c:3051 [inline] check_prevs_add kernel/locking/lockdep.c:3174 [inline] validate_chain+0x1dfb/0x8240 kernel/locking/lockdep.c:3789 __lock_acquire+0x1382/0x2b00 kernel/locking/lockdep.c:5015 lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5625 lock_sock_nested+0xc6/0x110 net/core/sock.c:3191 lock_sock include/net/sock.h:1612 [inline] rfcomm_sk_state_change+0x63/0x300 net/bluetooth/rfcomm/sock.c:73 __rfcomm_dlc_close+0x2cc/0x480 net/bluetooth/rfcomm/core.c:489 rfcomm_process_dlcs+0x92/0x620 net/bluetooth/rfcomm/core.c:1844 rfcomm_process_sessions+0x2f6/0x3f0 net/bluetooth/rfcomm/core.c:2003 rfcomm_run+0x195/0x2c0 net/bluetooth/rfcomm/core.c:2086 kthread+0x453/0x480 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. For information about bisection process see: https://goo.gl/tpsmEJ#bisection syzbot can test patches for this issue, for details see: https://goo.gl/tpsmEJ#testing-patches
