------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 2 PID: 11131 at lib/refcount.c:28 refcount_warn_saturate+0x14a/0x210 lib/refcount.c:28 Modules linked in: CPU: 2 UID: 0 PID: 11131 Comm: syz.4.2306 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 RIP: 0010:refcount_warn_saturate+0x14a/0x210 lib/refcount.c:28 Code: ff 89 de e8 d8 8d 1a fd 84 db 0f 85 66 ff ff ff e8 eb 92 1a fd c6 05 22 eb c8 0b 01 90 48 c7 c7 80 c3 ef 8b e8 47 12 d9 fc 90 <0f> 0b 90 90 e9 43 ff ff ff e8 c8 92 1a fd 0f b6 1d fd ea c8 0b 31 RSP: 0018:ffffc9000471f9f8 EFLAGS: 00010286 RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffc90028443000 RDX: 0000000000080000 RSI: ffffffff817aee65 RDI: 0000000000000001 RBP: ffff888013258078 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000001 R12: ffff888013259400 R13: ffff888013258078 R14: ffffffff85d7d930 R15: ffffffff90657f20 FS: 0000000000000000(0000) GS:ffff888097a10000(0063) knlGS:00000000f54ddb40 CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 CR2: 0000000032b1dffc CR3: 000000004c44e000 CR4: 0000000000352ef0 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 lib/klist.c:206 [inline] klist_put+0x11b/0x1b0 lib/klist.c:217 klist_del lib/klist.c:230 [inline] klist_remove+0x13f/0x2e0 lib/klist.c:249 device_move+0x12d/0x10d0 drivers/base/core.c:4615 hci_conn_del_sysfs+0x81/0x180 net/bluetooth/hci_sysfs.c:75 hci_conn_cleanup net/bluetooth/hci_conn.c:173 [inline] hci_conn_del+0x657/0x1180 net/bluetooth/hci_conn.c:1217 hci_conn_hash_flush+0x186/0x260 net/bluetooth/hci_conn.c:2610 hci_dev_do_reset net/bluetooth/hci_core.c:566 [inline] hci_dev_reset+0x249/0x610 net/bluetooth/hci_core.c:610 hci_sock_ioctl+0x493/0x7d0 net/bluetooth/hci_sock.c:1140 hci_sock_compat_ioctl+0x43/0x80 net/bluetooth/hci_sock.c:1181 compat_sock_ioctl+0x176/0x730 net/socket.c:3564 __do_compat_sys_ioctl fs/ioctl.c:695 [inline] __se_compat_sys_ioctl fs/ioctl.c:638 [inline] __ia32_compat_sys_ioctl+0x242/0x370 fs/ioctl.c:638 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0x7c/0x300 arch/x86/entry/syscall_32.c:306 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:331 entry_SYSENTER_compat_after_hwframe+0x84/0x8e RIP: 0023:0xf70ed579 Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 RSP: 002b:00000000f54dd55c EFLAGS: 00000296 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00000000400448cb RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 ---------------- Code disassembly (best guess), 2 bytes skipped: 0: 10 06 adc %al,(%rsi) 2: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi 6: 10 07 adc %al,(%rdi) 8: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi c: 10 08 adc %cl,(%rax) e: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi 1e: 00 51 52 add %dl,0x52(%rcx) 21: 55 push %rbp 22: 89 e5 mov %esp,%ebp 24: 0f 34 sysenter 26: cd 80 int $0x80 * 28: 5d pop %rbp <-- trapping instruction 29: 5a pop %rdx 2a: 59 pop %rcx 2b: c3 ret 2c: 90 nop 2d: 90 nop 2e: 90 nop 2f: 90 nop 30: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi 37: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi