------------[ cut here ]------------
dst_release underflow
WARNING: CPU: 0 PID: 25920 at net/core/dst.c:175 dst_release net/core/dst.c:175 [inline]
WARNING: CPU: 0 PID: 25920 at net/core/dst.c:175 dst_release+0xd2/0xe0 net/core/dst.c:169
Modules linked in:
CPU: 0 PID: 25920 Comm: syz-executor.3 Not tainted 5.14.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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 3f e5 59 fa 85 db 74 a4 e9 38 e5 09 02 e8 f1 dd 59 fa 48 c7 c7 e0 c6 8a 8a c6 05 29 4d 3c 06 01 e8 58 77 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:ffffc90009b77bd0 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000040000 RSI: ffffffff815d85c5 RDI: fffff5200136ef6c
RBP: ffffe8ffffab1960 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff815d23fe R11: 0000000000000000 R12: ffff888020c92bc0
R13: 00000000ffffffff R14: 0000000000000007 R15: 0000000000000000
FS:  00007f9bf9404700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2cf30000 CR3: 0000000076bb0000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 dst_cache_destroy net/core/dst_cache.c:160 [inline]
 dst_cache_destroy+0xcb/0x190 net/core/dst_cache.c:152
 ipip6_dev_free net/ipv6/sit.c:1412 [inline]
 sit_init_net+0x7d8/0xaa0 net/ipv6/sit.c:1934
 ops_init+0xaf/0x470 net/core/net_namespace.c:140
 setup_net+0x40f/0xa30 net/core/net_namespace.c:333
 copy_net_ns+0x319/0x760 net/core/net_namespace.c:474
 create_new_namespaces+0x3f6/0xb20 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0xc1/0x1f0 kernel/nsproxy.c:226
 ksys_unshare+0x445/0x920 kernel/fork.c:3002
 __do_sys_unshare kernel/fork.c:3076 [inline]
 __se_sys_unshare kernel/fork.c:3074 [inline]
 __x64_sys_unshare+0x2d/0x40 kernel/fork.c:3074
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4665e9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f9bf9404188 EFLAGS: 00000246 ORIG_RAX: 0000000000000110
RAX: ffffffffffffffda RBX: 000000000056c0f0 RCX: 00000000004665e9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000040000000
RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c0f0
R13: 00007ffdc4c349df R14: 00007f9bf9404300 R15: 0000000000022000
----------------
Code disassembly (best guess):
   0:	89 c3                	mov    %eax,%ebx
   2:	89 c6                	mov    %eax,%esi
   4:	e8 3f e5 59 fa       	callq  0xfa59e548
   9:	85 db                	test   %ebx,%ebx
   b:	74 a4                	je     0xffffffb1
   d:	e9 38 e5 09 02       	jmpq   0x209e54a
  12:	e8 f1 dd 59 fa       	callq  0xfa59de08
  17:	48 c7 c7 e0 c6 8a 8a 	mov    $0xffffffff8a8ac6e0,%rdi
  1e:	c6 05 29 4d 3c 06 01 	movb   $0x1,0x63c4d29(%rip)        # 0x63c4d4e
  25:	e8 58 77 cc 01       	callq  0x1cc7782
  2a:	0f 0b                	ud2     <-- trapping instruction
  2c:	eb c6                	jmp    0xfffffff4
  2e:	66 2e 0f 1f 84 00 00 	nopw   %cs:0x0(%rax,%rax,1)
  35:	00 00 00 
  38:	41 56                	push   %r14
  3a:	41 55                	push   %r13
  3c:	41 54                	push   %r12
  3e:	55                   	push   %rbp
  3f:	48                   	rex.W