Bluetooth: hci2: Opcode 0x0c1a failed: -4 Bluetooth: hci2: Error when powering off device on rfkill (-4) Bluetooth: hci4: Opcode 0x0c1a failed: -4 Bluetooth: hci4: Error when powering off device on rfkill (-4) ------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: lib/refcount.c:28 at refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28, CPU#0: syz.0.2160/13967 Modules linked in: CPU: 0 UID: 0 PID: 13967 Comm: syz.0.2160 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28 Code: 84 89 fe 0a 67 48 0f b9 3a eb 4a e8 a8 fd 32 fd 48 8d 3d 81 89 fe 0a 67 48 0f b9 3a eb 37 e8 95 fd 32 fd 48 8d 3d 7e 89 fe 0a <67> 48 0f b9 3a eb 24 e8 82 fd 32 fd 48 8d 3d 7b 89 fe 0a 67 48 0f RSP: 0018:ffffc9000c5277b8 EFLAGS: 00010287 RAX: ffffffff848dfa2b RBX: 0000000000000003 RCX: 0000000000080000 RDX: ffffc9000c039000 RSI: 000000000001b5ff RDI: ffffffff8f8c83b0 RBP: 0000000000000000 R08: ffff888051ed5b80 R09: 0000000000000005 R10: 0000000000000004 R11: 0000000000000002 R12: ffff888021fc1000 R13: ffff888057081c60 R14: ffff888057081c78 R15: dffffc0000000000 FS: 00007f3775ec16c0(0000) GS:ffff888125e1e000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c314df9 CR3: 000000004c02c000 CR4: 00000000003526f0 Call Trace: __refcount_sub_and_test include/linux/refcount.h:400 [inline] __refcount_dec_and_test include/linux/refcount.h:432 [inline] refcount_dec_and_test include/linux/refcount.h:450 [inline] kref_put include/linux/kref.h:64 [inline] klist_dec_and_del+0x3c7/0x3d0 lib/klist.c:206 klist_put lib/klist.c:217 [inline] klist_del lib/klist.c:230 [inline] klist_remove+0x1bd/0x340 lib/klist.c:249 device_move+0x193/0x730 drivers/base/core.c:4615 hci_conn_del_sysfs+0xb8/0x1a0 net/bluetooth/hci_sysfs.c:75 hci_conn_cleanup net/bluetooth/hci_conn.c:173 [inline] hci_conn_del+0xc36/0x1240 net/bluetooth/hci_conn.c:1234 hci_conn_hash_flush+0x191/0x260 net/bluetooth/hci_conn.c:2638 hci_dev_close_sync+0x821/0x1100 net/bluetooth/hci_sync.c:5326 hci_dev_do_close+0x30/0xc0 net/bluetooth/hci_core.c:501 hci_rfkill_set_block+0x21d/0x330 net/bluetooth/hci_core.c:929 rfkill_set_block+0x1d2/0x440 net/rfkill/core.c:346 rfkill_fop_write+0x44b/0x570 net/rfkill/core.c:1301 vfs_write+0x27e/0xb30 fs/read_write.c:684 ksys_write+0x145/0x250 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f3774f8f749 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f3775ec1038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f37751e5fa0 RCX: 00007f3774f8f749 RDX: 0000000000000008 RSI: 0000200000000080 RDI: 0000000000000003 RBP: 00007f3775013f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f37751e6038 R14: 00007f37751e5fa0 R15: 00007fff2ca62db8 ---------------- Code disassembly (best guess): 0: 84 89 fe 0a 67 48 test %cl,0x48670afe(%rcx) 6: 0f b9 3a ud1 (%rdx),%edi 9: eb 4a jmp 0x55 b: e8 a8 fd 32 fd call 0xfd32fdb8 10: 48 8d 3d 81 89 fe 0a lea 0xafe8981(%rip),%rdi # 0xafe8998 17: 67 48 0f b9 3a ud1 (%edx),%rdi 1c: eb 37 jmp 0x55 1e: e8 95 fd 32 fd call 0xfd32fdb8 23: 48 8d 3d 7e 89 fe 0a lea 0xafe897e(%rip),%rdi # 0xafe89a8 * 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction 2f: eb 24 jmp 0x55 31: e8 82 fd 32 fd call 0xfd32fdb8 36: 48 8d 3d 7b 89 fe 0a lea 0xafe897b(%rip),%rdi # 0xafe89b8 3d: 67 addr32 3e: 48 rex.W 3f: 0f .byte 0xf