==================================================================
BUG: KMSAN: uninit-value in __arch_swab32 arch/x86/include/uapi/asm/swab.h:10 [inline]
BUG: KMSAN: uninit-value in __fswab32 include/uapi/linux/swab.h:59 [inline]
BUG: KMSAN: uninit-value in erspan_rcv net/ipv4/ip_gre.c:282 [inline]
BUG: KMSAN: uninit-value in gre_rcv+0x11a3/0x1900 net/ipv4/ip_gre.c:422
CPU: 1 PID: 16952 Comm: syz-executor0 Not tainted 4.20.0-rc5+ #112
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1c9/0x220 lib/dump_stack.c:113
 kmsan_report+0x12d/0x290 mm/kmsan/kmsan.c:684
 __msan_warning+0x76/0xc0 mm/kmsan/kmsan_instr.c:316
 __arch_swab32 arch/x86/include/uapi/asm/swab.h:10 [inline]
 __fswab32 include/uapi/linux/swab.h:59 [inline]
 erspan_rcv net/ipv4/ip_gre.c:282 [inline]
 gre_rcv+0x11a3/0x1900 net/ipv4/ip_gre.c:422
 gre_rcv+0x2e6/0x3c0 net/ipv4/gre_demux.c:143
 ip_local_deliver_finish+0x7b8/0xef0 net/ipv4/ip_input.c:215
 NF_HOOK include/linux/netfilter.h:289 [inline]
 ip_local_deliver+0x44b/0x510 net/ipv4/ip_input.c:256
 dst_input include/net/dst.h:450 [inline]
 ip_rcv_finish net/ipv4/ip_input.c:415 [inline]
 NF_HOOK include/linux/netfilter.h:289 [inline]
 ip_rcv+0x6b6/0x740 net/ipv4/ip_input.c:524
 __netif_receive_skb_one_core net/core/dev.c:4941 [inline]
 __netif_receive_skb net/core/dev.c:5051 [inline]
 process_backlog+0x756/0x10f0 net/core/dev.c:5859
 napi_poll net/core/dev.c:6282 [inline]
 net_rx_action+0x876/0x1b40 net/core/dev.c:6348
 __do_softirq+0x5ff/0xab6 kernel/softirq.c:293
 do_softirq_own_stack+0x49/0x80 arch/x86/entry/entry_64.S:1035
 </IRQ>
 do_softirq kernel/softirq.c:338 [inline]
 __local_bh_enable_ip+0x228/0x260 kernel/softirq.c:190
 local_bh_enable+0x36/0x40 include/linux/bottom_half.h:32
 rcu_read_unlock_bh include/linux/rcupdate.h:696 [inline]
 ip_finish_output2+0x145f/0x1590 net/ipv4/ip_output.c:231
 ip_finish_output+0xd40/0xfe0 net/ipv4/ip_output.c:317
 NF_HOOK_COND include/linux/netfilter.h:278 [inline]
 ip_mc_output+0x10ea/0x16f0 net/ipv4/ip_output.c:390
 dst_output include/net/dst.h:444 [inline]
 ip_local_out net/ipv4/ip_output.c:124 [inline]
 ip_send_skb+0x178/0x370 net/ipv4/ip_output.c:1442
 udp_send_skb+0x1439/0x1920 net/ipv4/udp.c:829
 udp_sendmsg+0x3ae6/0x4160 net/ipv4/udp.c:1116
 inet_sendmsg+0x4ab/0x750 net/ipv4/af_inet.c:798
 sock_sendmsg_nosec net/socket.c:621 [inline]
 sock_sendmsg net/socket.c:631 [inline]
 ___sys_sendmsg+0xdbc/0x11d0 net/socket.c:2116
 __sys_sendmmsg+0x56b/0xa90 net/socket.c:2211
 __do_sys_sendmmsg net/socket.c:2240 [inline]
 __se_sys_sendmmsg+0xbd/0xe0 net/socket.c:2237
 __x64_sys_sendmmsg+0x56/0x70 net/socket.c:2237
 do_syscall_64+0xcd/0x110 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x457679
Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fdf55d6cc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000457679
RDX: 0000000000000001 RSI: 0000000020004e00 RDI: 0000000000000003
RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fdf55d6d6d4
R13: 00000000004c3e34 R14: 00000000004d6c58 R15: 00000000ffffffff

Uninit was stored to memory at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:247 [inline]
 kmsan_save_stack mm/kmsan/kmsan.c:262 [inline]
 kmsan_internal_chain_origin+0x162/0x260 mm/kmsan/kmsan.c:470
 kmsan_memcpy_memmove_metadata+0x1a9/0xf70 mm/kmsan/kmsan.c:345
 kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:363
 __msan_memcpy+0x61/0x70 mm/kmsan/kmsan_instr.c:148
 pskb_expand_head+0x352/0x18d0 net/core/skbuff.c:1469
 __skb_cow include/linux/skbuff.h:2962 [inline]
 skb_cow_head include/linux/skbuff.h:2996 [inline]
 ip_tunnel_xmit+0x34d9/0x3b50 net/ipv4/ip_tunnel.c:780
 __gre_xmit net/ipv4/ip_gre.c:451 [inline]
 erspan_xmit+0x1949/0x3730 net/ipv4/ip_gre.c:749
 __netdev_start_xmit include/linux/netdevice.h:4356 [inline]
 netdev_start_xmit include/linux/netdevice.h:4365 [inline]
 xmit_one net/core/dev.c:3252 [inline]
 dev_hard_start_xmit+0x627/0xc80 net/core/dev.c:3268
 sch_direct_xmit+0x59b/0x890 net/sched/sch_generic.c:327
 qdisc_restart net/sched/sch_generic.c:390 [inline]
 __qdisc_run+0x1d0a/0x3510 net/sched/sch_generic.c:398
 qdisc_run include/net/pkt_sched.h:121 [inline]
 __dev_xmit_skb net/core/dev.c:3447 [inline]
 __dev_queue_xmit+0x1ca1/0x3cf0 net/core/dev.c:3806
 dev_queue_xmit+0x4b/0x60 net/core/dev.c:3871
 neigh_resolve_output+0xab7/0xb50 net/core/neighbour.c:1382
 neigh_output include/net/neighbour.h:484 [inline]
 ip_finish_output2+0x144a/0x1590 net/ipv4/ip_output.c:229
 ip_finish_output+0xd40/0xfe0 net/ipv4/ip_output.c:317
 NF_HOOK_COND include/linux/netfilter.h:278 [inline]
 ip_mc_output+0x10ea/0x16f0 net/ipv4/ip_output.c:390
 dst_output include/net/dst.h:444 [inline]
 ip_local_out net/ipv4/ip_output.c:124 [inline]
 ip_send_skb+0x178/0x370 net/ipv4/ip_output.c:1442
 udp_send_skb+0x1439/0x1920 net/ipv4/udp.c:829
 udp_sendmsg+0x3ae6/0x4160 net/ipv4/udp.c:1116
 inet_sendmsg+0x4ab/0x750 net/ipv4/af_inet.c:798
 sock_sendmsg_nosec net/socket.c:621 [inline]
 sock_sendmsg net/socket.c:631 [inline]
 ___sys_sendmsg+0xdbc/0x11d0 net/socket.c:2116
 __sys_sendmmsg+0x56b/0xa90 net/socket.c:2211
 __do_sys_sendmmsg net/socket.c:2240 [inline]
 __se_sys_sendmmsg+0xbd/0xe0 net/socket.c:2237
 __x64_sys_sendmmsg+0x56/0x70 net/socket.c:2237
 do_syscall_64+0xcd/0x110 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:247 [inline]
 kmsan_internal_poison_shadow+0x92/0x150 mm/kmsan/kmsan.c:170
 kmsan_kmalloc+0xa1/0x100 mm/kmsan/kmsan_hooks.c:186
 kmsan_slab_alloc+0xe/0x10 mm/kmsan/kmsan_hooks.c:195
 slab_post_alloc_hook mm/slab.h:446 [inline]
 slab_alloc_node mm/slub.c:2759 [inline]
 __kmalloc_node_track_caller+0xf06/0x1120 mm/slub.c:4383
 __kmalloc_reserve net/core/skbuff.c:137 [inline]
 __alloc_skb+0x318/0xa40 net/core/skbuff.c:205
 alloc_skb include/linux/skbuff.h:998 [inline]
 alloc_skb_with_frags+0x1c9/0xa80 net/core/skbuff.c:5220
 sock_alloc_send_pskb+0xb5d/0x1140 net/core/sock.c:2083
 sock_alloc_send_skb+0xca/0xe0 net/core/sock.c:2100
 __ip_append_data+0x2c89/0x4280 net/ipv4/ip_output.c:982
 ip_make_skb+0x3b0/0x8b0 net/ipv4/ip_output.c:1508
 udp_sendmsg+0x3721/0x4160 net/ipv4/udp.c:1111
 inet_sendmsg+0x4ab/0x750 net/ipv4/af_inet.c:798
 sock_sendmsg_nosec net/socket.c:621 [inline]
 sock_sendmsg net/socket.c:631 [inline]
 ___sys_sendmsg+0xdbc/0x11d0 net/socket.c:2116
 __sys_sendmmsg+0x56b/0xa90 net/socket.c:2211
 __do_sys_sendmmsg net/socket.c:2240 [inline]
 __se_sys_sendmmsg+0xbd/0xe0 net/socket.c:2237
 __x64_sys_sendmmsg+0x56/0x70 net/socket.c:2237
 do_syscall_64+0xcd/0x110 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
==================================================================