=====================================================
BUG: KMSAN: uninit-value in __skb_checksum_complete+0x372/0x4d0 net/core/skbuff.c:3389
 __skb_checksum_complete+0x372/0x4d0 net/core/skbuff.c:3389
 nf_ip_checksum+0x2df/0x670 net/netfilter/utils.c:36
 nf_nat_icmp_reply_translation+0x244/0x820 net/netfilter/nf_nat_proto.c:578
 nf_nat_ipv4_fn net/netfilter/nf_nat_proto.c:637 [inline]
 nf_nat_ipv4_local_fn+0x1e8/0x8d0 net/netfilter/nf_nat_proto.c:763
 nf_hook_entry_hookfn include/linux/netfilter.h:142 [inline]
 nf_hook_slow+0xf1/0x3c0 net/netfilter/core.c:614
 nf_hook include/linux/netfilter.h:257 [inline]
 __ip_local_out+0x719/0x7b0 net/ipv4/ip_output.c:115
 ip_local_out net/ipv4/ip_output.c:124 [inline]
 ip_send_skb net/ipv4/ip_output.c:1586 [inline]
 ip_push_pending_frames+0x10a/0x410 net/ipv4/ip_output.c:1606
 icmp_push_reply+0x643/0x6b0 net/ipv4/icmp.c:389
 __icmp_send+0x17dc/0x1870 net/ipv4/icmp.c:765
 ipv4_send_dest_unreach net/ipv4/route.c:1239 [inline]
 ipv4_link_failure+0x69b/0xac0 net/ipv4/route.c:1246
 dst_link_failure include/net/dst.h:423 [inline]
 arp_error_report+0xd7/0x140 net/ipv4/arp.c:296
 neigh_invalidate+0x2be/0x710 net/core/neighbour.c:1079
 neigh_timer_handler+0xabd/0x12d0 net/core/neighbour.c:1166
 call_timer_fn+0x45/0x4e0 kernel/time/timer.c:1700
 expire_timers kernel/time/timer.c:1751 [inline]
 __run_timers+0x861/0xf90 kernel/time/timer.c:2022
 run_timer_softirq+0x68/0xe0 kernel/time/timer.c:2035
 __do_softirq+0x1c9/0x7c5 kernel/softirq.c:571
 invoke_softirq kernel/softirq.c:445 [inline]
 __irq_exit_rcu+0xe5/0x220 kernel/softirq.c:650
 irq_exit_rcu+0x12/0x20 kernel/softirq.c:662
 sysvec_apic_timer_interrupt+0x9e/0xc0 arch/x86/kernel/apic/apic.c:1107
 asm_sysvec_apic_timer_interrupt+0x1f/0x30 arch/x86/include/asm/idtentry.h:645
 __msan_metadata_ptr_for_load_4+0x31/0x40 mm/kmsan/instrumentation.c:91
 inet_twsk_purge+0xbb8/0xc00 net/ipv4/inet_timewait_sock.c:288
 dccp_v6_exit_batch+0x23/0x30 net/dccp/ipv6.c:1122
 ops_exit_list net/core/net_namespace.c:174 [inline]
 setup_net+0xe48/0x1320 net/core/net_namespace.c:361
 copy_net_ns+0x69f/0xd40 net/core/net_namespace.c:490
 create_new_namespaces+0x717/0xdb0 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0x17a/0x2b0 kernel/nsproxy.c:228
 ksys_unshare+0x867/0x1250 kernel/fork.c:3200
 __do_sys_unshare kernel/fork.c:3271 [inline]
 __se_sys_unshare kernel/fork.c:3269 [inline]
 __x64_sys_unshare+0x48/0x70 kernel/fork.c:3269
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Uninit was stored to memory at:
 csum_partial_copy_nocheck include/net/checksum.h:53 [inline]
 skb_copy_and_csum_bits+0xf4/0x10f0 net/core/skbuff.c:3276
 icmp_glue_bits+0x91/0x280 net/ipv4/icmp.c:353
 __ip_append_data+0x537d/0x6430 net/ipv4/ip_output.c:1161
 ip_append_data+0x1f1/0x260 net/ipv4/ip_output.c:1343
 icmp_push_reply+0xad/0x6b0 net/ipv4/icmp.c:370
 __icmp_send+0x17dc/0x1870 net/ipv4/icmp.c:765
 ipv4_send_dest_unreach net/ipv4/route.c:1239 [inline]
 ipv4_link_failure+0x69b/0xac0 net/ipv4/route.c:1246
 dst_link_failure include/net/dst.h:423 [inline]
 arp_error_report+0xd7/0x140 net/ipv4/arp.c:296
 neigh_invalidate+0x2be/0x710 net/core/neighbour.c:1079
 neigh_timer_handler+0xabd/0x12d0 net/core/neighbour.c:1166
 call_timer_fn+0x45/0x4e0 kernel/time/timer.c:1700
 expire_timers kernel/time/timer.c:1751 [inline]
 __run_timers+0x861/0xf90 kernel/time/timer.c:2022
 run_timer_softirq+0x68/0xe0 kernel/time/timer.c:2035
 __do_softirq+0x1c9/0x7c5 kernel/softirq.c:571

Uninit was stored to memory at:
 pskb_expand_head+0x312/0x1a30 net/core/skbuff.c:2001
 __skb_cow include/linux/skbuff.h:3562 [inline]
 skb_cow_head include/linux/skbuff.h:3596 [inline]
 ip_tunnel_xmit+0x3a1f/0x4230 net/ipv4/ip_tunnel.c:806
 __gre_xmit net/ipv4/ip_gre.c:469 [inline]
 erspan_xmit+0x13d1/0x1f00 net/ipv4/ip_gre.c:715
 __netdev_start_xmit include/linux/netdevice.h:4883 [inline]
 netdev_start_xmit include/linux/netdevice.h:4897 [inline]
 xmit_one net/core/dev.c:3580 [inline]
 dev_hard_start_xmit+0x253/0xa20 net/core/dev.c:3596
 sch_direct_xmit+0x3f7/0xdc0 net/sched/sch_generic.c:342
 __dev_xmit_skb net/core/dev.c:3807 [inline]
 __dev_queue_xmit+0x3601/0x5ac0 net/core/dev.c:4212
 dev_queue_xmit include/linux/netdevice.h:3053 [inline]
 neigh_resolve_output+0x99a/0xab0 net/core/neighbour.c:1583
 neigh_output include/net/neighbour.h:546 [inline]
 ip_finish_output2+0x1834/0x1a60 net/ipv4/ip_output.c:228
 __ip_finish_output+0x266/0x720
 ip_finish_output+0x4b/0x420 net/ipv4/ip_output.c:316
 NF_HOOK_COND include/linux/netfilter.h:291 [inline]
 ip_output+0x215/0x500 net/ipv4/ip_output.c:430
 dst_output include/net/dst.h:444 [inline]
 ip_local_out net/ipv4/ip_output.c:126 [inline]
 ip_send_skb+0x110/0x2a0 net/ipv4/ip_output.c:1586
 udp_send_skb+0xff9/0x1b00 net/ipv4/udp.c:978
 udp_sendmsg+0x3145/0x3510 net/ipv4/udp.c:1265
 udpv6_sendmsg+0x13ef/0x4370
 inet6_sendmsg+0x105/0x190 net/ipv6/af_inet6.c:651
 sock_sendmsg_nosec net/socket.c:724 [inline]
 sock_sendmsg net/socket.c:747 [inline]
 ____sys_sendmsg+0xa24/0xe40 net/socket.c:2501
 ___sys_sendmsg+0x2a1/0x3f0 net/socket.c:2555
 __sys_sendmmsg+0x411/0xa50 net/socket.c:2641
 __do_sys_sendmmsg net/socket.c:2670 [inline]
 __se_sys_sendmmsg net/socket.c:2667 [inline]
 __x64_sys_sendmmsg+0xbc/0x120 net/socket.c:2667
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Uninit was created at:
 slab_post_alloc_hook+0x12d/0xb60 mm/slab.h:774
 slab_alloc_node mm/slub.c:3452 [inline]
 kmem_cache_alloc_node+0x543/0xab0 mm/slub.c:3497
 kmalloc_reserve+0x148/0x470 net/core/skbuff.c:520
 __alloc_skb+0x3a7/0x850 net/core/skbuff.c:606
 alloc_skb include/linux/skbuff.h:1277 [inline]
 alloc_skb_with_frags+0xbd/0xbb0 net/core/skbuff.c:6318
 sock_alloc_send_pskb+0xaad/0xc30 net/core/sock.c:2734
 sock_alloc_send_skb include/net/sock.h:1860 [inline]
 __ip_append_data+0x448d/0x6430 net/ipv4/ip_output.c:1120
 ip_make_skb+0x1ee/0x640 net/ipv4/ip_output.c:1652
 udp_sendmsg+0x2ffe/0x3510 net/ipv4/udp.c:1260
 udpv6_sendmsg+0x13ef/0x4370
 inet6_sendmsg+0x105/0x190 net/ipv6/af_inet6.c:651
 sock_sendmsg_nosec net/socket.c:724 [inline]
 sock_sendmsg net/socket.c:747 [inline]
 ____sys_sendmsg+0xa24/0xe40 net/socket.c:2501
 ___sys_sendmsg+0x2a1/0x3f0 net/socket.c:2555
 __sys_sendmmsg+0x411/0xa50 net/socket.c:2641
 __do_sys_sendmmsg net/socket.c:2670 [inline]
 __se_sys_sendmmsg net/socket.c:2667 [inline]
 __x64_sys_sendmmsg+0xbc/0x120 net/socket.c:2667
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

CPU: 1 PID: 28786 Comm: syz-executor.4 Tainted: G        W          6.3.0-rc5-syzkaller-g9189d4cb6980 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/30/2023
=====================================================