------------[ cut here ]------------
refcount_t: increment on 0; use-after-free.
WARNING: CPU: 1 PID: 11677 at lib/refcount.c:156 refcount_inc_checked /lib/refcount.c:156 [inline]
WARNING: CPU: 1 PID: 11677 at lib/refcount.c:156 refcount_inc_checked+0x61/0x70 /lib/refcount.c:154
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 11677 Comm: syz-executor.2 Not tainted 5.2.0+ #64
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack /lib/dump_stack.c:77 [inline]
 dump_stack+0x16f/0x1f0 /lib/dump_stack.c:113
 panic+0x2dc/0x755 /kernel/panic.c:219
 __warn.cold+0x20/0x4c /kernel/panic.c:576
 report_bug+0x263/0x2b0 /lib/bug.c:186
 fixup_bug /arch/x86/kernel/traps.c:179 [inline]
 fixup_bug /arch/x86/kernel/traps.c:174 [inline]
 do_error_trap+0x11b/0x200 /arch/x86/kernel/traps.c:272
 do_invalid_op+0x37/0x50 /arch/x86/kernel/traps.c:291
 invalid_op+0x23/0x30 /arch/x86/entry/entry_64.S:1026
RIP: 0010:refcount_inc_checked /lib/refcount.c:156 [inline]
RIP: 0010:refcount_inc_checked+0x61/0x70 /lib/refcount.c:154
Code: 1d 2c 9e 67 06 31 ff 89 de e8 9b 24 38 fe 84 db 75 dd e8 52 23 38 fe 48 c7 c7 40 d6 c5 87 c6 05 0c 9e 67 06 01 e8 87 4a 0a fe <0f> 0b eb c1 90 90 90 90 90 90 90 90 90 90 90 55 48 89 e5 41 57 41
RSP: 0018:ffff8880ae909bf0 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000100 RSI: ffffffff815b9de2 RDI: ffffed1015d21370
RBP: ffff8880ae909c00 R08: ffff88808f656000 R09: fffffbfff14a6d65
R10: fffffbfff14a6d64 R11: ffffffff8a536b27 R12: ffff888062536100
R13: ffff8880625360e8 R14: ffff888093e37708 R15: ffff888093e376e0
 sock_hold /./include/net/sock.h:649 [inline]
 sk_add_node /./include/net/sock.h:701 [inline]
 nr_insert_socket+0x2d/0xe0 /net/netrom/af_netrom.c:137
 nr_rx_frame+0x1605/0x1e73 /net/netrom/af_netrom.c:1023
 nr_loopback_timer+0x7b/0x170 /net/netrom/nr_loopback.c:59
 call_timer_fn+0x1ac/0x700 /kernel/time/timer.c:1322
 expire_timers /kernel/time/timer.c:1366 [inline]
 __run_timers /kernel/time/timer.c:1685 [inline]
 __run_timers /kernel/time/timer.c:1653 [inline]
 run_timer_softirq+0x66c/0x16a0 /kernel/time/timer.c:1698
 __do_softirq+0x30d/0x970 /kernel/softirq.c:292
 invoke_softirq /kernel/softirq.c:373 [inline]
 irq_exit+0x1d0/0x200 /kernel/softirq.c:413
 exiting_irq /./arch/x86/include/asm/apic.h:537 [inline]
 smp_apic_timer_interrupt+0x14e/0x550 /arch/x86/kernel/apic/apic.c:1095
 apic_timer_interrupt+0xf/0x20 /arch/x86/entry/entry_64.S:828
 </IRQ>
RIP: 0010:arch_local_irq_restore /./arch/x86/include/asm/paravirt.h:768 [inline]
RIP: 0010:lock_acquire+0x20b/0x400 /kernel/locking/lockdep.c:4416
Code: 4c 08 00 00 00 00 00 00 48 c1 e8 03 80 3c 10 00 0f 85 c7 01 00 00 48 83 3d 81 a1 7a 07 00 0f 84 3d 01 00 00 48 8b 7d c8 57 9d <0f> 1f 44 00 00 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 65 8b
RSP: 0018:ffff88805cd378a8 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13
RAX: 1ffffffff11a5c72 RBX: ffff88808f656000 RCX: ffffffff8157f352
RDX: dffffc0000000000 RSI: 0000000000000008 RDI: 0000000000000282
RBP: ffff88805cd378f0 R08: 0000000000004b7b R09: fffffbfff14a6d51
R10: ffff88808f656850 R11: ffff88808f656000 R12: ffff888089ccc848
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000001
 __might_fault /mm/memory.c:4441 [inline]
 __might_fault+0x15e/0x1e0 /mm/memory.c:4426
 _copy_from_user+0x30/0x1a0 /lib/usercopy.c:10
 copy_from_user /./include/linux/uaccess.h:144 [inline]
 copy_msghdr_from_user+0xa0/0x440 /net/socket.c:2191
 ___sys_sendmsg+0x10b/0x920 /net/socket.c:2256
 __sys_sendmmsg+0x1bf/0x4e0 /net/socket.c:2413
 __do_sys_sendmmsg /net/socket.c:2442 [inline]
 __se_sys_sendmmsg /net/socket.c:2439 [inline]
 __x64_sys_sendmmsg+0x9d/0x100 /net/socket.c:2439
 do_syscall_64+0xfd/0x6a0 /arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459819
Code: fd b7 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fb251fbec78 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000459819
RDX: 03a301e0909ff6cd RSI: 00000000200003c0 RDI: 0000000000000004
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0080000000000000 R11: 0000000000000246 R12: 00007fb251fbf6d4
R13: 00000000004c6ec3 R14: 00000000004dc2b0 R15: 00000000ffffffff
Kernel Offset: disabled
Rebooting in 86400 seconds..