------------[ cut here ]------------
refcount_t: increment on 0; use-after-free.
WARNING: CPU: 1 PID: 15933 at lib/refcount.c:156 refcount_inc_checked+0x2b/0x30 lib/refcount.c:156
Kernel panic - not syncing: panic_on_warn set ...
kobject: 'loop2' (00000000ee7f726e): kobject_uevent_env
CPU: 1 PID: 15933 Comm: syz-executor4 Not tainted 5.3.0-rc5 #1
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+0x113/0x167 lib/dump_stack.c:113
kobject: 'loop2' (00000000ee7f726e): fill_kobj_path: path = '/devices/virtual/block/loop2'
 panic+0x223/0x4ee kernel/panic.c:219
 __warn.cold.10+0x1b/0x45 kernel/panic.c:576
 report_bug+0x1a4/0x200 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:179 [inline]
 do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:272
 do_invalid_op+0x36/0x40 arch/x86/kernel/traps.c:291
 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1028
RIP: 0010:refcount_inc_checked+0x2b/0x30 lib/refcount.c:156
Code: 48 89 e5 e8 97 fe ff ff 84 c0 74 02 5d c3 80 3d a2 df fc 05 00 75 f5 48 c7 c7 40 e4 23 87 c6 05 92 df fc 05 01 e8 27 0a 3a fe <0f> 0b 5d c3 90 55 48 89 e5 41 56 41 55 49 89 fd 48 c7 c7 a0 e4 23
RSP: 0018:ffff8881a4aaf2f0 EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffff8881cf5a5400 RCX: 0000000000000000
RDX: 0000000000000402 RSI: 0000000000000008 RDI: ffffffff89eb5ec0
RBP: ffff8881a4aaf2f0 R08: ffffed103b6240e3 R09: ffffed103b6240e3
R10: ffffed103b6240e2 R11: ffff8881db120717 R12: 00000000000003e8
R13: dffffc0000000000 R14: ffff8881bf479980 R15: ffff8881ccef1262
 igmp_start_timer+0x93/0xc0 net/ipv4/igmp.c:222
 igmp_mod_timer net/ipv4/igmp.c:260 [inline]
 igmp_heard_query net/ipv4/igmp.c:1054 [inline]
 igmp_rcv+0x11a3/0x2740 net/ipv4/igmp.c:1089
 ip_protocol_deliver_rcu+0x55b/0x760 net/ipv4/ip_input.c:204
 ip_local_deliver_finish+0x1ec/0x2e0 net/ipv4/ip_input.c:231
 NF_HOOK include/linux/netfilter.h:305 [inline]
 ip_local_deliver+0x2f7/0x440 net/ipv4/ip_input.c:252
 dst_input include/net/dst.h:442 [inline]
 ip_rcv_finish+0x16f/0x280 net/ipv4/ip_input.c:413
 NF_HOOK include/linux/netfilter.h:305 [inline]
 ip_rcv+0xcb/0x2e0 net/ipv4/ip_input.c:523
 __netif_receive_skb_one_core+0x132/0x190 net/core/dev.c:5004
 __netif_receive_skb+0x1f/0x1b0 net/core/dev.c:5118
 netif_receive_skb_internal+0xca/0x2a0 net/core/dev.c:5208
 napi_frags_finish net/core/dev.c:5759 [inline]
 napi_gro_frags+0x947/0xb60 net/core/dev.c:5833
kobject: 'loop5' (00000000a633583d): kobject_uevent_env
 tun_get_user+0x24c5/0x3880 drivers/net/tun.c:1974
kobject: 'loop5' (00000000a633583d): fill_kobj_path: path = '/devices/virtual/block/loop5'
kobject: 'loop3' (000000001aa44d62): kobject_uevent_env
 tun_chr_write_iter+0xaf/0x150 drivers/net/tun.c:2020
 call_write_iter include/linux/fs.h:1870 [inline]
 do_iter_readv_writev+0x530/0xa70 fs/read_write.c:693
kobject: 'loop3' (000000001aa44d62): fill_kobj_path: path = '/devices/virtual/block/loop3'
kobject: 'loop0' (00000000b1bbc0ec): kobject_uevent_env
 do_iter_write+0x128/0x540 fs/read_write.c:970
kobject: 'loop0' (00000000b1bbc0ec): fill_kobj_path: path = '/devices/virtual/block/loop0'
 vfs_writev+0x16d/0x2d0 fs/read_write.c:1015
kobject: 'loop0' (00000000b1bbc0ec): kobject_uevent_env
 do_writev+0x112/0x2e0 fs/read_write.c:1058
 __do_sys_writev fs/read_write.c:1131 [inline]
 __se_sys_writev fs/read_write.c:1128 [inline]
 __x64_sys_writev+0x70/0xb0 fs/read_write.c:1128
 do_syscall_64+0xd6/0x550 arch/x86/entry/common.c:296
kobject: 'loop0' (00000000b1bbc0ec): fill_kobj_path: path = '/devices/virtual/block/loop0'
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457681
Code: 75 14 b8 14 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 54 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:00007f9884b0fba0 EFLAGS: 00000293 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 000000000000002a RCX: 0000000000457681
RDX: 0000000000000001 RSI: 00007f9884b0fbf0 RDI: 00000000000000f0
RBP: 0000000020000240 R08: 00000000000000f0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 00000000ffffffff
R13: 00000000004d79d8 R14: 00000000004c4954 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..