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BUG: KMSAN: uninit-value in __neigh_create+0x21fe/0x2630 net/core/neighbour.c:563
CPU: 1 PID: 12127 Comm: syz-executor4 Not tainted 4.20.0-rc5+ #2
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __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:682
 __msan_warning+0x76/0xc0 mm/kmsan/kmsan_instr.c:316
 __neigh_create+0x21fe/0x2630 net/core/neighbour.c:563
 ip_finish_output2+0xa28/0x1590 net/ipv4/ip_output.c:224
 ip_finish_output+0xd40/0xfe0 net/ipv4/ip_output.c:317
 NF_HOOK_COND include/linux/netfilter.h:278 [inline]
 ip_output+0x559/0x620 net/ipv4/ip_output.c:405
 dst_output include/net/dst.h:444 [inline]
 ip_local_out+0x164/0x1d0 net/ipv4/ip_output.c:124
 iptunnel_xmit+0x8d3/0xe20 net/ipv4/ip_tunnel_core.c:91
 ip_tunnel_xmit+0x378c/0x3b50 net/ipv4/ip_tunnel.c:787
 __gre_xmit net/ipv4/ip_gre.c:451 [inline]
 ipgre_xmit+0xddc/0xec0 net/ipv4/ip_gre.c:705
 __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
 __dev_queue_xmit+0x3173/0x3cf0 net/core/dev.c:3838
 dev_queue_xmit+0x4b/0x60 net/core/dev.c:3871
 packet_snd net/packet/af_packet.c:2928 [inline]
 packet_sendmsg+0x7cbd/0x9200 net/packet/af_packet.c:2953
 sock_sendmsg_nosec net/socket.c:621 [inline]
 sock_sendmsg net/socket.c:631 [inline]
 ___sys_sendmsg+0xdbc/0x11d0 net/socket.c:2116
 __sys_sendmsg net/socket.c:2154 [inline]
 __do_sys_sendmsg net/socket.c:2163 [inline]
 __se_sys_sendmsg+0x305/0x460 net/socket.c:2161
 __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2161
 do_syscall_64+0xcd/0x110 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x457669
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:00007fc3ef4cbc78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457669
RDX: 0000000000000000 RSI: 00000000200004c0 RDI: 0000000000000004
RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fc3ef4cc6d4
R13: 00000000004c43f7 R14: 00000000004d7388 R15: 00000000ffffffff

Uninit was created at:
No stack
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