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BUG: KCSAN: data-race in ip_tunnel_xmit / ip_tunnel_xmit

read to 0xffff8880b4fc1198 of 8 bytes by task 10596 on cpu 0:
 ip_tunnel_xmit+0x12c0/0x1400 net/ipv4/ip_tunnel.c:756
 ipip_tunnel_xmit+0x2c7/0x310 net/ipv4/ipip.c:305
 __netdev_start_xmit include/linux/netdevice.h:4413 [inline]
 netdev_start_xmit include/linux/netdevice.h:4427 [inline]
 xmit_one net/core/dev.c:3199 [inline]
 dev_hard_start_xmit+0xef/0x430 net/core/dev.c:3215
 __dev_queue_xmit+0x14ab/0x1b40 net/core/dev.c:3792
 dev_queue_xmit+0x21/0x30 net/core/dev.c:3825
 neigh_direct_output+0x1f/0x30 net/core/neighbour.c:1530
 neigh_output include/net/neighbour.h:511 [inline]
 ip_finish_output2+0x4af/0xe40 net/ipv4/ip_output.c:228
 __ip_finish_output net/ipv4/ip_output.c:308 [inline]
 __ip_finish_output+0x23a/0x490 net/ipv4/ip_output.c:290
 ip_finish_output+0x41/0x160 net/ipv4/ip_output.c:318
 NF_HOOK_COND include/linux/netfilter.h:294 [inline]
 ip_output+0xdf/0x210 net/ipv4/ip_output.c:432
 dst_output include/net/dst.h:436 [inline]
 ip_local_out+0x74/0x90 net/ipv4/ip_output.c:125
 iptunnel_xmit+0x356/0x520 net/ipv4/ip_tunnel_core.c:78
 ip_tunnel_xmit+0x9aa/0x1400 net/ipv4/ip_tunnel.c:818
 __gre_xmit+0x389/0x4e0 net/ipv4/ip_gre.c:444
 ipgre_xmit+0x332/0x630 net/ipv4/ip_gre.c:628
 __netdev_start_xmit include/linux/netdevice.h:4413 [inline]
 netdev_start_xmit include/linux/netdevice.h:4427 [inline]
 xmit_one net/core/dev.c:3199 [inline]
 dev_hard_start_xmit+0xef/0x430 net/core/dev.c:3215
 __dev_queue_xmit+0x14ab/0x1b40 net/core/dev.c:3792
 dev_queue_xmit+0x21/0x30 net/core/dev.c:3825
 __bpf_tx_skb net/core/filter.c:2060 [inline]
 __bpf_redirect_common net/core/filter.c:2099 [inline]
 __bpf_redirect+0x4b4/0x710 net/core/filter.c:2106
 ____bpf_clone_redirect net/core/filter.c:2139 [inline]
 bpf_clone_redirect+0x1a5/0x1f0 net/core/filter.c:2111
 bpf_prog_bebbfe2050753572+0x4a1/0x1000
 bpf_test_run+0x1c3/0x490 net/bpf/test_run.c:44
 bpf_prog_test_run_skb+0x4da/0x840 net/bpf/test_run.c:310
 bpf_prog_test_run kernel/bpf/syscall.c:2117 [inline]
 __do_sys_bpf+0x1664/0x2b90 kernel/bpf/syscall.c:2893
 __se_sys_bpf kernel/bpf/syscall.c:2834 [inline]
 __x64_sys_bpf+0x4c/0x60 kernel/bpf/syscall.c:2834
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff8880b4fc1198 of 8 bytes by task 10597 on cpu 1:
 ip_tunnel_xmit+0x12d3/0x1400 net/ipv4/ip_tunnel.c:756
 ipip_tunnel_xmit+0x2c7/0x310 net/ipv4/ipip.c:305
 __netdev_start_xmit include/linux/netdevice.h:4413 [inline]
 netdev_start_xmit include/linux/netdevice.h:4427 [inline]
 xmit_one net/core/dev.c:3199 [inline]
 dev_hard_start_xmit+0xef/0x430 net/core/dev.c:3215
 __dev_queue_xmit+0x14ab/0x1b40 net/core/dev.c:3792
 dev_queue_xmit+0x21/0x30 net/core/dev.c:3825
 neigh_direct_output+0x1f/0x30 net/core/neighbour.c:1530
 neigh_output include/net/neighbour.h:511 [inline]
 ip_finish_output2+0x4af/0xe40 net/ipv4/ip_output.c:228
 __ip_finish_output net/ipv4/ip_output.c:308 [inline]
 __ip_finish_output+0x23a/0x490 net/ipv4/ip_output.c:290
 ip_finish_output+0x41/0x160 net/ipv4/ip_output.c:318
 NF_HOOK_COND include/linux/netfilter.h:294 [inline]
 ip_output+0xdf/0x210 net/ipv4/ip_output.c:432
 dst_output include/net/dst.h:436 [inline]
 ip_local_out+0x74/0x90 net/ipv4/ip_output.c:125
 iptunnel_xmit+0x356/0x520 net/ipv4/ip_tunnel_core.c:78
 ip_tunnel_xmit+0x9aa/0x1400 net/ipv4/ip_tunnel.c:818
 __gre_xmit+0x389/0x4e0 net/ipv4/ip_gre.c:444
 ipgre_xmit+0x332/0x630 net/ipv4/ip_gre.c:628
 __netdev_start_xmit include/linux/netdevice.h:4413 [inline]
 netdev_start_xmit include/linux/netdevice.h:4427 [inline]
 xmit_one net/core/dev.c:3199 [inline]
 dev_hard_start_xmit+0xef/0x430 net/core/dev.c:3215
 __dev_queue_xmit+0x14ab/0x1b40 net/core/dev.c:3792
 dev_queue_xmit+0x21/0x30 net/core/dev.c:3825
 __bpf_tx_skb net/core/filter.c:2060 [inline]
 __bpf_redirect_common net/core/filter.c:2099 [inline]
 __bpf_redirect+0x4b4/0x710 net/core/filter.c:2106
 ____bpf_clone_redirect net/core/filter.c:2139 [inline]
 bpf_clone_redirect+0x1a5/0x1f0 net/core/filter.c:2111
 bpf_prog_bebbfe2050753572+0x304/0x1000
 bpf_test_run+0x1c3/0x490 net/bpf/test_run.c:44
 bpf_prog_test_run_skb+0x4da/0x840 net/bpf/test_run.c:310
 bpf_prog_test_run kernel/bpf/syscall.c:2117 [inline]
 __do_sys_bpf+0x1664/0x2b90 kernel/bpf/syscall.c:2893
 __se_sys_bpf kernel/bpf/syscall.c:2834 [inline]
 __x64_sys_bpf+0x4c/0x60 kernel/bpf/syscall.c:2834
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 10597 Comm: syz-executor.0 Not tainted 5.4.0-rc6+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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