refcount_t: increment on 0; use-after-free. ------------[ cut here ]------------ WARNING: CPU: 1 PID: 28118 at lib/refcount.c:153 refcount_inc lib/refcount.c:153 [inline] WARNING: CPU: 1 PID: 28118 at lib/refcount.c:153 refcount_inc.cold+0x18/0x1f lib/refcount.c:151 kobject: 'loop0' (ffff8880a49d8660): kobject_uevent_env Kernel panic - not syncing: panic_on_warn set ... CPU: 1 PID: 28118 Comm: syz-executor.4 Not tainted 4.14.135 #31 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+0x138/0x19c lib/dump_stack.c:53 panic+0x1f2/0x426 kernel/panic.c:182 kobject: 'loop0' (ffff8880a49d8660): fill_kobj_path: path = '/devices/virtual/block/loop0' __warn.cold+0x2f/0x36 kernel/panic.c:546 report_bug+0x216/0x254 lib/bug.c:186 fixup_bug arch/x86/kernel/traps.c:177 [inline] fixup_bug arch/x86/kernel/traps.c:172 [inline] do_error_trap+0x1bb/0x310 arch/x86/kernel/traps.c:295 kobject: 'loop5' (ffff8880a4b62220): kobject_uevent_env do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:314 invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:960 TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies. Check SNMP counters. RIP: 0010:refcount_inc lib/refcount.c:153 [inline] RIP: 0010:refcount_inc.cold+0x18/0x1f lib/refcount.c:151 RSP: 0018:ffff88804ee4f9c0 EFLAGS: 00010286 RAX: 000000000000002b RBX: ffffffff86fac020 RCX: 0000000000000000 RDX: 0000000000020e6b RSI: ffffffff814b1975 RDI: ffffed1009dc9f2e RBP: ffff88804ee4f9c8 R08: 000000000000002b R09: ffff88804d350f88 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880a7d43538 R13: 0000000000000000 R14: ffff8880a7d43500 R15: ffff8880645e5ea0 kref_get include/linux/kref.h:47 [inline] kobject_get+0x5b/0x70 lib/kobject.c:596 kset_get include/linux/kobject.h:210 [inline] kobj_kset_join lib/kobject.c:169 [inline] kobject_add_internal.part.0+0xfc/0x340 lib/kobject.c:220 kobject: 'loop5' (ffff8880a4b62220): fill_kobj_path: path = '/devices/virtual/block/loop5' kobject_add_internal lib/kobject.c:205 [inline] kobject_add_varg lib/kobject.c:364 [inline] kobject_add+0x11f/0x180 lib/kobject.c:409 kobject: 'loop2' (ffff8880a4a8a960): kobject_uevent_env class_dir_create_and_add drivers/base/core.c:1484 [inline] get_device_parent.isra.0+0x415/0x560 drivers/base/core.c:1539 device_add+0x2d3/0x1490 drivers/base/core.c:1795 kobject: 'loop2' (ffff8880a4a8a960): fill_kobj_path: path = '/devices/virtual/block/loop2' hci_register_dev+0x2d9/0x810 net/bluetooth/hci_core.c:3118 __vhci_create_device+0x2a6/0x560 drivers/bluetooth/hci_vhci.c:139 vhci_create_device drivers/bluetooth/hci_vhci.c:163 [inline] vhci_get_user drivers/bluetooth/hci_vhci.c:219 [inline] vhci_write+0x2a1/0x437 drivers/bluetooth/hci_vhci.c:299 kobject: 'loop1' (ffff8880a4a2ef60): kobject_uevent_env call_write_iter include/linux/fs.h:1777 [inline] new_sync_write fs/read_write.c:469 [inline] __vfs_write+0x4a7/0x6b0 fs/read_write.c:482 vfs_write+0x198/0x500 fs/read_write.c:544 SYSC_write fs/read_write.c:590 [inline] SyS_write+0xfd/0x230 fs/read_write.c:582 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292 TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies. Check SNMP counters. entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x459829 RSP: 002b:00007f267f654c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459829 RDX: 0000000000000002 RSI: 0000000020000000 RDI: 0000000000000003 RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f267f6556d4 R13: 00000000004c9b0d R14: 00000000004e1178 R15: 00000000ffffffff Kernel Offset: disabled Rebooting in 86400 seconds..