bisecting fixing commit since ef244c3088856cf048c77231653b4c92a7b2213c building syzkaller on 5ea87a6638e52a94361b26b8576a1605585815fb testing commit ef244c3088856cf048c77231653b4c92a7b2213c with gcc (GCC) 8.1.0 kernel signature: 339800b2839c39cecc47ea5b6e1773c568f68664 all runs: crashed: WARNING: ODEBUG bug in rfcomm_dlc_free testing current HEAD 312017a460d5ea31d646e7148e400e13db799ddc testing commit 312017a460d5ea31d646e7148e400e13db799ddc with gcc (GCC) 8.1.0 kernel signature: cba883f818d58d04a1a45f0e33ebb8cf0cbc8307 all runs: crashed: WARNING: ODEBUG bug in rfcomm_dlc_free revisions tested: 2, total time: 23m34.333170711s (build: 16m36.008287458s, test: 6m30.117886597s) the crash still happens on HEAD commit msg: Linux 4.19.89 crash: WARNING: ODEBUG bug in rfcomm_dlc_free IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_team: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): team_slave_1: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_hsr: link becomes ready ------------[ cut here ]------------ ODEBUG: free active (active state 0) object type: timer_list hint: rfcomm_dlc_timeout+0x0/0x50 include/linux/list.h:64 WARNING: CPU: 1 PID: 7012 at lib/debugobjects.c:328 debug_print_object+0x168/0x210 lib/debugobjects.c:325 Kernel panic - not syncing: panic_on_warn set ... CPU: 1 PID: 7012 Comm: syz-executor.2 Not tainted 4.19.89-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+0x123/0x177 lib/dump_stack.c:118 panic+0x1cd/0x375 kernel/panic.c:186 __warn.cold.8+0x1b/0x3e kernel/panic.c:541 report_bug+0x1a4/0x200 lib/bug.c:186 fixup_bug arch/x86/kernel/traps.c:178 [inline] do_error_trap+0x200/0x350 arch/x86/kernel/traps.c:296 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:316 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:1037 RIP: 0010:debug_print_object+0x168/0x210 lib/debugobjects.c:325 Code: ff 86 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 92 00 00 00 48 8b 14 dd 40 22 ff 86 4c 89 fe 48 c7 c7 80 17 ff 86 e8 6b 62 48 fe <0f> 0b 83 05 1b 89 c2 05 01 48 83 c4 18 5b 41 5c 41 5d 41 5e 41 5f RSP: 0018:ffff888096e4f868 EFLAGS: 00010086 RAX: 0000000000000000 RBX: 0000000000000003 RCX: 0000000000000000 RDX: 0000000000000004 RSI: 0000000000000008 RDI: ffffffff89a7e6e0 RBP: ffff888096e4f8a8 R08: ffffed1015d63ee3 R09: ffffed1015d63ee2 R10: ffffed1015d63ee2 R11: ffff8880aeb1f717 R12: 0000000000000001 R13: ffffffff87fa51c0 R14: ffffffff8152e460 R15: ffffffff86ff1e60 __debug_check_no_obj_freed lib/debugobjects.c:785 [inline] debug_check_no_obj_freed+0x264/0x472 lib/debugobjects.c:817 kfree+0xbd/0x220 mm/slab.c:3821 rfcomm_dlc_free+0x19/0x20 net/bluetooth/rfcomm/core.c:328 rfcomm_dlc_put include/net/bluetooth/rfcomm.h:258 [inline] __rfcomm_create_dev net/bluetooth/rfcomm/tty.c:417 [inline] rfcomm_create_dev net/bluetooth/rfcomm/tty.c:486 [inline] rfcomm_dev_ioctl+0x1435/0x18b0 net/bluetooth/rfcomm/tty.c:588 rfcomm_sock_ioctl+0x71/0xa0 net/bluetooth/rfcomm/sock.c:902 sock_do_ioctl+0xd9/0x230 net/socket.c:950 sock_ioctl+0x281/0x500 net/socket.c:1074 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:501 [inline] do_vfs_ioctl+0x196/0x10c0 fs/ioctl.c:688 ksys_ioctl+0x62/0x90 fs/ioctl.c:705 __do_sys_ioctl fs/ioctl.c:712 [inline] __se_sys_ioctl fs/ioctl.c:710 [inline] __x64_sys_ioctl+0x6e/0xb0 fs/ioctl.c:710 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x459f49 Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f0000913c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459f49 RDX: 0000000020000100 RSI: 00000000400452c8 RDI: 0000000000000005 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f00009146d4 R13: 00000000004c288e R14: 00000000004d6538 R15: 00000000ffffffff ======================================================