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BUG: KCSAN: data-race in ip_tunnel_xmit / ip_tunnel_xmit

read to 0xffff8880acf6a138 of 8 bytes by task 20583 on cpu 1:
 ip_tunnel_xmit+0xca0/0x1400 net/ipv4/ip_tunnel.c:827
 __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+0x7db/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:2120 [inline]
 __do_sys_bpf+0x1664/0x2b90 kernel/bpf/syscall.c:2896
 __se_sys_bpf kernel/bpf/syscall.c:2837 [inline]
 __x64_sys_bpf+0x4c/0x60 kernel/bpf/syscall.c:2837
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff8880acf6a138 of 8 bytes by task 20603 on cpu 0:
 ip_tunnel_xmit+0xcb3/0x1400 net/ipv4/ip_tunnel.c:827
 __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+0x32a/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:2120 [inline]
 __do_sys_bpf+0x1664/0x2b90 kernel/bpf/syscall.c:2896
 __se_sys_bpf kernel/bpf/syscall.c:2837 [inline]
 __x64_sys_bpf+0x4c/0x60 kernel/bpf/syscall.c:2837
 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: 0 PID: 20603 Comm: syz-executor.0 Not tainted 5.4.0-rc7+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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