------------[ cut here ]------------
refcount_t: increment on 0; use-after-free.
WARNING: CPU: 1 PID: 28477 at lib/refcount.c:156 refcount_inc_checked /lib/refcount.c:156 [inline]
WARNING: CPU: 1 PID: 28477 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: 28477 Comm: syz-executor.2 Not tainted 5.2.0+ #61
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+0x172/0x1f0 /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+0x14/0x20 /arch/x86/entry/entry_64.S:1008
RIP: 0010:refcount_inc_checked /lib/refcount.c:156 [inline]
RIP: 0010:refcount_inc_checked+0x61/0x70 /lib/refcount.c:154
Code: 1d 38 94 64 06 31 ff 89 de e8 3b 50 36 fe 84 db 75 dd e8 f2 4e 36 fe 48 c7 c7 c0 c1 c5 87 c6 05 18 94 64 06 01 e8 57 c1 07 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: ffffffff815c1ef6 RDI: ffffed1015d21370
RBP: ffff8880ae909c00 R08: ffff8880677ac0c0 R09: fffffbfff14a6579
R10: fffffbfff14a6578 R11: ffffffff8a532bc7 R12: ffff8880620d8d40
R13: ffff8880620d8d28 R14: ffff888087b7e908 R15: ffff888087b7e8e0
 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/0x780 /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+0x697/0x17a0 /kernel/time/timer.c:1698
 __do_softirq+0x262/0x98c /kernel/softirq.c:292
 invoke_softirq /kernel/softirq.c:373 [inline]
 irq_exit+0x19b/0x1e0 /kernel/softirq.c:413
 exiting_irq /./arch/x86/include/asm/apic.h:537 [inline]
 smp_apic_timer_interrupt+0x1a3/0x610 /arch/x86/kernel/apic/apic.c:1095
 apic_timer_interrupt+0xf/0x20 /arch/x86/entry/entry_64.S:828
 </IRQ>
RIP: 0010:check_kcov_mode /kernel/kcov.c:68 [inline]
RIP: 0010:write_comp_data+0x10/0x70 /kernel/kcov.c:123
Code: 00 00 48 8b 11 48 83 c2 01 48 39 d0 76 07 48 89 34 d1 48 89 11 5d c3 0f 1f 00 65 4c 8b 04 25 c0 fd 01 00 65 8b 05 b8 98 8f 7e <a9> 00 01 1f 00 75 51 41 8b 80 f0 12 00 00 83 f8 03 75 45 49 8b 80
RSP: 0018:ffff88808ff87718 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 0000000080000001 RBX: 00007f4356caf000 RCX: ffffffff819d19af
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000007
RBP: ffff88808ff87720 R08: ffff8880677ac0c0 R09: ffff8880677ac948
R10: fffffbfff1348f6f R11: ffffffff89a47b7f R12: ffffea0002900980
R13: ffff88808ff87a00 R14: ffffea0002900980 R15: dffffc0000000000
 compound_head /./include/linux/page-flags.h:174 [inline]
 PageSlab /./include/linux/page-flags.h:323 [inline]
 page_mapcount /./include/linux/mm.h:707 [inline]
 zap_pte_range /mm/memory.c:1060 [inline]
 zap_pmd_range /mm/memory.c:1161 [inline]
 zap_pud_range /mm/memory.c:1190 [inline]
 zap_p4d_range /mm/memory.c:1211 [inline]
 unmap_page_range+0xdff/0x2170 /mm/memory.c:1232
 unmap_single_vma+0x19d/0x300 /mm/memory.c:1277
 unmap_vmas+0x135/0x280 /mm/memory.c:1309
 exit_mmap+0x2ba/0x530 /mm/mmap.c:3145
 __mmput /kernel/fork.c:1064 [inline]
 mmput+0x179/0x4d0 /kernel/fork.c:1085
 exit_mm /kernel/exit.c:547 [inline]
 do_exit+0x84e/0x2ea0 /kernel/exit.c:864
 do_group_exit+0x135/0x360 /kernel/exit.c:981
 get_signal+0x47c/0x2500 /kernel/signal.c:2728
 do_signal+0x87/0x1670 /arch/x86/kernel/signal.c:815
 exit_to_usermode_loop+0x286/0x380 /arch/x86/entry/common.c:159
 prepare_exit_to_usermode /arch/x86/entry/common.c:194 [inline]
 syscall_return_slowpath /arch/x86/entry/common.c:274 [inline]
 do_syscall_64+0x5a9/0x6a0 /arch/x86/entry/common.c:299
 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:00007f4354b69cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 000000000075bf28 RCX: 0000000000459819
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000075bf28
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000075bf2c
R13: 00007ffedf3d43bf R14: 00007f4354b6a9c0 R15: 000000000075bf2c
Kernel Offset: disabled
Rebooting in 86400 seconds..