------------[ cut here ]------------
dst_release underflow
WARNING: CPU: 1 PID: 10 at net/core/dst.c:175 dst_release net/core/dst.c:175 [inline]
WARNING: CPU: 1 PID: 10 at net/core/dst.c:175 dst_release+0xd2/0xe0 net/core/dst.c:169
Modules linked in:
CPU: 0 PID: 10 Comm: kworker/u4:1 Not tainted 5.14.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
RIP: 0010:dst_release net/core/dst.c:175 [inline]
RIP: 0010:dst_release+0xd2/0xe0 net/core/dst.c:169
Code: 89 c3 89 c6 e8 cf 5f 5a fa 85 db 74 a4 e9 ee b2 09 02 e8 81 58 5a fa 48 c7 c7 20 b9 8a 8a c6 05 26 b7 3c 06 01 e8 bf 40 cc 01 <0f> 0b eb c6 66 2e 0f 1f 84 00 00 00 00 00 41 56 41 55 41 54 55 48
RSP: 0018:ffffc90000cf79f0 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff888010a61c40 RSI: ffffffff815d6855 RDI: fffff5200019ef30
RBP: ffffe8ffffcca640 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff815d068e R11: 0000000000000000 R12: ffffe8ffffcca648
R13: 000000008718232f R14: 0000000000000007 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005557ea8c4690 CR3: 000000002aef1000 CR4: 0000000000350ef0
Call Trace:
 dst_cache_destroy net/core/dst_cache.c:160 [inline]
 dst_cache_destroy+0xcb/0x190 net/core/dst_cache.c:152
 ip_tunnel_dev_free+0x21/0x60 net/ipv4/ip_tunnel.c:1010
 netdev_run_todo+0x6b4/0xa80 net/core/dev.c:10625
 ip_tunnel_delete_nets+0x3a4/0x5b0 net/ipv4/ip_tunnel.c:1123
 ops_exit_list+0x10d/0x160 net/core/net_namespace.c:178
 cleanup_net+0x4ea/0xb10 net/core/net_namespace.c:595
 process_one_work+0x98d/0x1630 kernel/workqueue.c:2276
 worker_thread+0x658/0x11f0 kernel/workqueue.c:2422
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295