netlink: 'syz.3.16': attribute type 11 has an invalid length.
=====================================
WARNING: bad unlock balance detected!
6.14.0-rc4-syzkaller #0 Not tainted
-------------------------------------
syz.3.16/3545 is trying to release lock (rtnl_mutex) at:
[<ffffffff82527a6c>] __rtnl_unlock+0x2c/0x60 net/core/rtnetlink.c:142
but there are no more locks to release!

other info that might help us debug this:
no locks held by syz.3.16/3545.

stack backtrace:
CPU: 0 UID: 0 PID: 3545 Comm: syz.3.16 Not tainted 6.14.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0xa3/0x100 lib/dump_stack.c:120
 print_unlock_imbalance_bug+0x182/0x1a0 kernel/locking/lockdep.c:5289
 __lock_release kernel/locking/lockdep.c:5518 [inline]
 lock_release+0x18d/0x2d0 kernel/locking/lockdep.c:5872
 __mutex_unlock_slowpath+0x38/0x1f0 kernel/locking/mutex.c:891
 __rtnl_unlock+0x2c/0x60 net/core/rtnetlink.c:142
 lwtunnel_valid_encap_type+0x201/0x370 net/core/lwtunnel.c:169
 lwtunnel_valid_encap_type_attr+0x73/0xb0 net/core/lwtunnel.c:209
 rtm_to_fib_config+0x305/0x440 net/ipv4/fib_frontend.c:808
 inet_rtm_newroute+0xdd/0x160 net/ipv4/fib_frontend.c:917
 rtnetlink_rcv_msg+0x456/0x4a0 net/core/rtnetlink.c:6919
 netlink_rcv_skb+0xe0/0x110 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x1e2/0x2d0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x34f/0x3e0 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:709 [inline]
 __sock_sendmsg+0x8e/0xb0 net/socket.c:724
 ____sys_sendmsg+0x1a5/0x200 net/socket.c:2564
 ___sys_sendmsg+0x28f/0x2d0 net/socket.c:2618
 __sys_sendmsg net/socket.c:2650 [inline]
 __do_sys_sendmsg net/socket.c:2655 [inline]
 __se_sys_sendmsg net/socket.c:2653 [inline]
 __x64_sys_sendmsg+0xeb/0x140 net/socket.c:2653
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xa0/0x180 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7ad6f8d169
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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f7ad7eaa038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f7ad71a5fa0 RCX: 00007f7ad6f8d169
RDX: 0000000000000000 RSI: 0000400000000000 RDI: 0000000000000003
RBP: 00007f7ad700e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f7ad71a5fa0 R15: 00007ffe37e0e9b8
 </TASK>