=====================================================
BUG: KMSAN: uninit-value in gre_rcv+0x1cb/0x1900 net/ipv4/ip_gre.c:409
CPU: 0 PID: 11488 Comm: syz-executor381 Not tainted 5.3.0-rc7+ #0
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+0x191/0x1f0 lib/dump_stack.c:113
 kmsan_report+0x13a/0x2b0 mm/kmsan/kmsan_report.c:108
 __msan_warning+0x73/0xe0 mm/kmsan/kmsan_instr.c:250
 __arch_swab32 arch/x86/include/uapi/asm/swab.h:10 [inline]
 __fswab32 include/uapi/linux/swab.h:59 [inline]
 gre_parse_header+0x1395/0x1690 net/ipv4/gre_demux.c:131
 gre_rcv+0x1cb/0x1900 net/ipv4/ip_gre.c:409
 gre_rcv+0x2dd/0x3c0 net/ipv4/gre_demux.c:155
 ip_protocol_deliver_rcu+0x722/0xbc0 net/ipv4/ip_input.c:204
 ip_local_deliver_finish net/ipv4/ip_input.c:231 [inline]
 NF_HOOK include/linux/netfilter.h:305 [inline]
 ip_local_deliver+0x62a/0x7c0 net/ipv4/ip_input.c:252
 dst_input include/net/dst.h:442 [inline]
 ip_rcv_finish net/ipv4/ip_input.c:413 [inline]
 NF_HOOK include/linux/netfilter.h:305 [inline]
 ip_rcv+0x6c5/0x740 net/ipv4/ip_input.c:523
 __netif_receive_skb_one_core net/core/dev.c:5004 [inline]
 __netif_receive_skb net/core/dev.c:5118 [inline]
 process_backlog+0xef5/0x1410 net/core/dev.c:5929
 napi_poll net/core/dev.c:6352 [inline]
 net_rx_action+0x74b/0x1950 net/core/dev.c:6418
 __do_softirq+0x4a1/0x83a kernel/softirq.c:293
 do_softirq_own_stack+0x49/0x80 arch/x86/entry/entry_64.S:1093
 </IRQ>
 do_softirq kernel/softirq.c:338 [inline]
 __local_bh_enable_ip+0x184/0x1d0 kernel/softirq.c:190
 local_bh_enable+0x36/0x40 include/linux/bottom_half.h:32
 rcu_read_unlock_bh include/linux/rcupdate.h:681 [inline]
 ip_finish_output2+0x20dc/0x25d0 net/ipv4/ip_output.c:229
 __ip_finish_output+0xaf8/0xda0 net/ipv4/ip_output.c:308
 ip_finish_output+0x2db/0x420 net/ipv4/ip_output.c:318
 NF_HOOK_COND include/linux/netfilter.h:294 [inline]
 ip_output+0x541/0x610 net/ipv4/ip_output.c:432
 dst_output include/net/dst.h:436 [inline]
 ip_local_out net/ipv4/ip_output.c:125 [inline]
 ip_send_skb+0x179/0x360 net/ipv4/ip_output.c:1554
 udp_send_skb+0xeda/0x1870 net/ipv4/udp.c:887
 udp_sendmsg+0x397c/0x4170 net/ipv4/udp.c:1174
 inet_sendmsg+0x276/0x2e0 net/ipv4/af_inet.c:807
 sock_sendmsg_nosec net/socket.c:637 [inline]
 sock_sendmsg net/socket.c:657 [inline]
 ___sys_sendmsg+0x12c4/0x1590 net/socket.c:2311
 __sys_sendmmsg+0x53a/0xae0 net/socket.c:2413
 __do_sys_sendmmsg net/socket.c:2442 [inline]
 __se_sys_sendmmsg+0xbd/0xe0 net/socket.c:2439
 __x64_sys_sendmmsg+0x56/0x70 net/socket.c:2439
 do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x4419e9
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 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 0f 83 7b 10 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffc09dd73a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000004419e9
RDX: 0400000000000030 RSI: 0000000020007fc0 RDI: 0000000000000003
RBP: 00007ffc09dd73c0 R08: 0000000001bbbbbb R09: 0000000001bbbbbb
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000402f80 R14: 0000000000000000 R15: 0000000000000000

Uninit was stored to memory at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:150 [inline]
 kmsan_internal_chain_origin+0xd2/0x170 mm/kmsan/kmsan.c:314
 kmsan_memcpy_memmove_metadata+0x25b/0x2d0 mm/kmsan/kmsan.c:247
 kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:267
 __msan_memcpy+0x56/0x70 mm/kmsan/kmsan_instr.c:129
 pskb_expand_head+0x38a/0x19f0 net/core/skbuff.c:1637
 __skb_cow include/linux/skbuff.h:3060 [inline]
 skb_cow_head include/linux/skbuff.h:3094 [inline]
 ip_tunnel_xmit+0x2971/0x3320 net/ipv4/ip_tunnel.c:811
 __gre_xmit net/ipv4/ip_gre.c:444 [inline]
 erspan_xmit+0x1ef8/0x35c0 net/ipv4/ip_gre.c:679
 __netdev_start_xmit include/linux/netdevice.h:4406 [inline]
 netdev_start_xmit include/linux/netdevice.h:4420 [inline]
 xmit_one net/core/dev.c:3280 [inline]
 dev_hard_start_xmit+0x51a/0xab0 net/core/dev.c:3296
 sch_direct_xmit+0x56c/0x18c0 net/sched/sch_generic.c:309
 __dev_xmit_skb net/core/dev.c:3477 [inline]
 __dev_queue_xmit+0x1e53/0x4270 net/core/dev.c:3838
 dev_queue_xmit+0x4b/0x60 net/core/dev.c:3902
 neigh_resolve_output+0xab7/0xb50 net/core/neighbour.c:1490
 neigh_output include/net/neighbour.h:511 [inline]
 ip_finish_output2+0x1a8e/0x25d0 net/ipv4/ip_output.c:228
 __ip_finish_output+0xaf8/0xda0 net/ipv4/ip_output.c:308
 ip_finish_output+0x2db/0x420 net/ipv4/ip_output.c:318
 NF_HOOK_COND include/linux/netfilter.h:294 [inline]
 ip_output+0x541/0x610 net/ipv4/ip_output.c:432
 dst_output include/net/dst.h:436 [inline]
 ip_local_out net/ipv4/ip_output.c:125 [inline]
 ip_send_skb+0x179/0x360 net/ipv4/ip_output.c:1554
 udp_send_skb+0xeda/0x1870 net/ipv4/udp.c:887
 udp_sendmsg+0x397c/0x4170 net/ipv4/udp.c:1174
 inet_sendmsg+0x276/0x2e0 net/ipv4/af_inet.c:807
 sock_sendmsg_nosec net/socket.c:637 [inline]
 sock_sendmsg net/socket.c:657 [inline]
 ___sys_sendmsg+0x12c4/0x1590 net/socket.c:2311
 __sys_sendmmsg+0x53a/0xae0 net/socket.c:2413
 __do_sys_sendmmsg net/socket.c:2442 [inline]
 __se_sys_sendmmsg+0xbd/0xe0 net/socket.c:2439
 __x64_sys_sendmmsg+0x56/0x70 net/socket.c:2439
 do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x63/0xe7

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:150 [inline]
 kmsan_internal_poison_shadow+0x53/0x100 mm/kmsan/kmsan.c:134
 kmsan_slab_alloc+0xaa/0x120 mm/kmsan/kmsan_hooks.c:103
 slab_alloc_node mm/slub.c:2790 [inline]
 __kmalloc_node_track_caller+0xb55/0x1320 mm/slub.c:4388
 __kmalloc_reserve net/core/skbuff.c:141 [inline]
 __alloc_skb+0x306/0xa10 net/core/skbuff.c:209
 alloc_skb include/linux/skbuff.h:1056 [inline]
 alloc_skb_with_frags+0x18c/0xa80 net/core/skbuff.c:5628
 sock_alloc_send_pskb+0xafd/0x10a0 net/core/sock.c:2232
 sock_alloc_send_skb+0xca/0xe0 net/core/sock.c:2249
 __ip_append_data+0x375d/0x52f0 net/ipv4/ip_output.c:1087
 ip_make_skb+0x392/0x890 net/ipv4/ip_output.c:1620
 udp_sendmsg+0x367e/0x4170 net/ipv4/udp.c:1169
 inet_sendmsg+0x276/0x2e0 net/ipv4/af_inet.c:807
 sock_sendmsg_nosec net/socket.c:637 [inline]
 sock_sendmsg net/socket.c:657 [inline]
 ___sys_sendmsg+0x12c4/0x1590 net/socket.c:2311
 __sys_sendmmsg+0x53a/0xae0 net/socket.c:2413
 __do_sys_sendmmsg net/socket.c:2442 [inline]
 __se_sys_sendmmsg+0xbd/0xe0 net/socket.c:2439
 __x64_sys_sendmmsg+0x56/0x70 net/socket.c:2439
 do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
=====================================================