------------[ cut here ]------------ refcount_t: increment on 0; use-after-free. WARNING: CPU: 0 PID: 10302 at lib/refcount.c:153 refcount_inc_checked+0x5d/0x70 lib/refcount.c:153 Kernel panic - not syncing: panic_on_warn set ... CPU: 0 PID: 10302 Comm: syz-executor3 Not tainted 4.19.0-rc8-next-20181019+ #98 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x244/0x39d lib/dump_stack.c:113 panic+0x2ad/0x55c kernel/panic.c:188 __warn.cold.8+0x20/0x45 kernel/panic.c:540 report_bug+0x254/0x2d0 lib/bug.c:186 fixup_bug arch/x86/kernel/traps.c:178 [inline] do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:271 do_invalid_op+0x36/0x40 arch/x86/kernel/traps.c:290 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:969 RIP: 0010:refcount_inc_checked+0x5d/0x70 lib/refcount.c:153 Code: 1d 9a 08 5d 06 31 ff 89 de e8 0f c9 ec fd 84 db 75 df e8 36 c8 ec fd 48 c7 c7 40 cb 40 88 c6 05 7a 08 5d 06 01 e8 53 70 b6 fd <0f> 0b eb c3 0f 1f 44 00 00 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 RSP: 0018:ffff880149dbece0 EFLAGS: 00010286 RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffc9000729c000 RDX: 000000000000fd92 RSI: ffffffff816585a5 RDI: 0000000000000005 RBP: ffff880149dbece8 R08: ffff8801879c0040 R09: ffffed003b5c3eda R10: ffffed003b5c3eda R11: ffff8801dae1f6d7 R12: 0000000000000000 R13: 0000000000000008 R14: ffff8801d9335500 R15: dffffc0000000000 igmp_start_timer+0xaf/0xe0 net/ipv4/igmp.c:217 igmp_mod_timer net/ipv4/igmp.c:255 [inline] igmp_heard_query net/ipv4/igmp.c:1026 [inline] igmp_rcv+0x190e/0x3020 net/ipv4/igmp.c:1061 ip_local_deliver_finish+0x2e9/0xda0 net/ipv4/ip_input.c:215 NF_HOOK include/linux/netfilter.h:289 [inline] ip_local_deliver+0x1e4/0x740 net/ipv4/ip_input.c:256 dst_input include/net/dst.h:450 [inline] ip_rcv_finish+0x1f9/0x300 net/ipv4/ip_input.c:415 NF_HOOK include/linux/netfilter.h:289 [inline] ip_rcv+0xe8/0x600 net/ipv4/ip_input.c:524 __netif_receive_skb_one_core+0x14d/0x200 net/core/dev.c:4941 __netif_receive_skb+0x27/0x1e0 net/core/dev.c:5051 netif_receive_skb_internal+0x11d/0x7f0 net/core/dev.c:5154 napi_frags_finish net/core/dev.c:5690 [inline] napi_gro_frags+0x74a/0xc80 net/core/dev.c:5763 tun_get_user+0x3189/0x4250 drivers/net/tun.c:1948 kobject: 'loop2' (00000000d49fa893): kobject_uevent_env kobject: 'loop2' (00000000d49fa893): fill_kobj_path: path = '/devices/virtual/block/loop2' kobject: 'loop4' (00000000798d03d5): kobject_uevent_env kobject: 'loop4' (00000000798d03d5): fill_kobj_path: path = '/devices/virtual/block/loop4' tun_chr_write_iter+0xb9/0x160 drivers/net/tun.c:1993 call_write_iter include/linux/fs.h:1844 [inline] do_iter_readv_writev+0x8b0/0xa80 fs/read_write.c:680 do_iter_write+0x185/0x5f0 fs/read_write.c:959 vfs_writev+0x1f1/0x360 fs/read_write.c:1004 do_writev+0x11a/0x310 fs/read_write.c:1039 __do_sys_writev fs/read_write.c:1112 [inline] __se_sys_writev fs/read_write.c:1109 [inline] __x64_sys_writev+0x75/0xb0 fs/read_write.c:1109 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457421 Code: 75 14 b8 14 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 34 b5 fb ff c3 48 83 ec 08 e8 1a 2d 00 00 48 89 04 24 b8 14 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 63 2d 00 00 48 89 d0 48 83 c4 08 48 3d 01 RSP: 002b:00007fb2c38cbba0 EFLAGS: 00000293 ORIG_RAX: 0000000000000014 RAX: ffffffffffffffda RBX: 000000000000002a RCX: 0000000000457421 RDX: 0000000000000001 RSI: 00007fb2c38cbbf0 RDI: 00000000000000f0 RBP: 0000000020000240 R08: 00000000000000f0 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000293 R12: 00007fb2c38cc6d4 R13: 00000000004c4890 R14: 00000000004d7b90 R15: 00000000ffffffff Kernel Offset: disabled Rebooting in 86400 seconds..