TCP: request_sock_subflow_v6: Possible SYN flooding on port [fe80::aa]:20002. Sending cookies.
=====================================================
BUG: KMSAN: uninit-value in subflow_token_join_request net/mptcp/subflow.c:91 [inline]
BUG: KMSAN: uninit-value in subflow_check_req+0x1028/0x15d0 net/mptcp/subflow.c:209
 subflow_token_join_request net/mptcp/subflow.c:91 [inline]
 subflow_check_req+0x1028/0x15d0 net/mptcp/subflow.c:209
 subflow_v6_route_req+0x269/0x410 net/mptcp/subflow.c:367
 tcp_conn_request+0x1515/0x4140 net/ipv4/tcp_input.c:7142
 subflow_v6_conn_request+0x3ee/0x510
 tcp_rcv_state_process+0x2e1/0x4ac0 net/ipv4/tcp_input.c:6637
 tcp_v6_do_rcv+0x11bf/0x1fe0 net/ipv6/tcp_ipv6.c:1669
 tcp_v6_rcv+0x480b/0x4fb0 net/ipv6/tcp_ipv6.c:1900
 ip6_protocol_deliver_rcu+0xda6/0x2a60 net/ipv6/ip6_input.c:438
 ip6_input_finish net/ipv6/ip6_input.c:483 [inline]
 NF_HOOK include/linux/netfilter.h:314 [inline]
 ip6_input+0x15d/0x430 net/ipv6/ip6_input.c:492
 dst_input include/net/dst.h:461 [inline]
 ip6_rcv_finish+0x5db/0x870 net/ipv6/ip6_input.c:79
 NF_HOOK include/linux/netfilter.h:314 [inline]
 ipv6_rcv+0xda/0x390 net/ipv6/ip6_input.c:310
 __netif_receive_skb_one_core net/core/dev.c:5527 [inline]
 __netif_receive_skb+0x1a6/0x5a0 net/core/dev.c:5641
 netif_receive_skb_internal net/core/dev.c:5727 [inline]
 netif_receive_skb+0x58/0x660 net/core/dev.c:5786
 tun_rx_batched+0x3ee/0x980 drivers/net/tun.c:1555
 tun_get_user+0x53af/0x66d0 drivers/net/tun.c:2002
 tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2048
 call_write_iter include/linux/fs.h:2020 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x8ef/0x1490 fs/read_write.c:584
 ksys_write+0x20f/0x4c0 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __ia32_sys_write+0x91/0xd0 fs/read_write.c:646
 do_syscall_32_irqs_on arch/x86/entry/common.c:164 [inline]
 __do_fast_syscall_32+0xa2/0x100 arch/x86/entry/common.c:230
 do_fast_syscall_32+0x37/0x70 arch/x86/entry/common.c:255
 do_SYSENTER_32+0x1f/0x30 arch/x86/entry/common.c:293
 entry_SYSENTER_compat_after_hwframe+0x70/0x7a

Local variable mp_opt created at:
 subflow_check_req+0x6d/0x15d0 net/mptcp/subflow.c:145
 subflow_v6_route_req+0x269/0x410 net/mptcp/subflow.c:367

CPU: 0 PID: 5243 Comm: syz-executor.2 Not tainted 6.6.0-syzkaller-10297-g21e80f3841c0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
=====================================================