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BUG: KCSAN: data-race in iptunnel_xmit / iptunnel_xmit

write to 0xffff88802345d140 of 8 bytes by task 25492 on cpu 0:
 iptunnel_xmit_stats syzkaller/managers/upstream-kcsan-gce/kernel/./include/net/ip_tunnels.h:459 [inline]
 iptunnel_xmit+0x422/0x4a0 syzkaller/managers/upstream-kcsan-gce/kernel/net/ipv4/ip_tunnel_core.c:87
 ip_tunnel_xmit+0xf2a/0x11c0 syzkaller/managers/upstream-kcsan-gce/kernel/net/ipv4/ip_tunnel.c:805
 __gre_xmit syzkaller/managers/upstream-kcsan-gce/kernel/net/ipv4/ip_gre.c:466 [inline]
 ipgre_xmit+0x4f5/0x550 syzkaller/managers/upstream-kcsan-gce/kernel/net/ipv4/ip_gre.c:648
 __netdev_start_xmit syzkaller/managers/upstream-kcsan-gce/kernel/./include/linux/netdevice.h:4776 [inline]
 netdev_start_xmit syzkaller/managers/upstream-kcsan-gce/kernel/./include/linux/netdevice.h:4790 [inline]
 xmit_one+0xf9/0x2e0 syzkaller/managers/upstream-kcsan-gce/kernel/net/core/dev.c:3574
 dev_hard_start_xmit syzkaller/managers/upstream-kcsan-gce/kernel/net/core/dev.c:3590 [inline]
 __dev_queue_xmit+0xf22/0x1570 syzkaller/managers/upstream-kcsan-gce/kernel/net/core/dev.c:4151
 dev_queue_xmit+0x13/0x20 syzkaller/managers/upstream-kcsan-gce/kernel/net/core/dev.c:4184
 __bpf_tx_skb syzkaller/managers/upstream-kcsan-gce/kernel/net/core/filter.c:2116 [inline]
 __bpf_redirect_no_mac syzkaller/managers/upstream-kcsan-gce/kernel/net/core/filter.c:2141 [inline]
 __bpf_redirect+0x54f/0x760 syzkaller/managers/upstream-kcsan-gce/kernel/net/core/filter.c:2164
 ____bpf_clone_redirect syzkaller/managers/upstream-kcsan-gce/kernel/net/core/filter.c:2448 [inline]
 bpf_clone_redirect+0x168/0x1c0 syzkaller/managers/upstream-kcsan-gce/kernel/net/core/filter.c:2420
 bpf_prog_ba8f84ee94c4fe67+0x56/0x620
 bpf_dispatcher_nop_func syzkaller/managers/upstream-kcsan-gce/kernel/./include/linux/bpf.h:651 [inline]
 bpf_test_run+0x278/0x460 syzkaller/managers/upstream-kcsan-gce/kernel/net/bpf/test_run.c:50
 bpf_prog_test_run_skb+0x714/0xe90 syzkaller/managers/upstream-kcsan-gce/kernel/net/bpf/test_run.c:582
 bpf_prog_test_run syzkaller/managers/upstream-kcsan-gce/kernel/kernel/bpf/syscall.c:3122 [inline]
 __do_sys_bpf+0x3971/0x9950 syzkaller/managers/upstream-kcsan-gce/kernel/kernel/bpf/syscall.c:4400
 __se_sys_bpf syzkaller/managers/upstream-kcsan-gce/kernel/kernel/bpf/syscall.c:4340 [inline]
 __x64_sys_bpf+0x3d/0x50 syzkaller/managers/upstream-kcsan-gce/kernel/kernel/bpf/syscall.c:4340
 do_syscall_64+0x39/0x80 syzkaller/managers/upstream-kcsan-gce/kernel/arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88802345d140 of 8 bytes by task 25499 on cpu 1:
 iptunnel_xmit_stats syzkaller/managers/upstream-kcsan-gce/kernel/./include/net/ip_tunnels.h:459 [inline]
 iptunnel_xmit+0x410/0x4a0 syzkaller/managers/upstream-kcsan-gce/kernel/net/ipv4/ip_tunnel_core.c:87
 ip_tunnel_xmit+0xf2a/0x11c0 syzkaller/managers/upstream-kcsan-gce/kernel/net/ipv4/ip_tunnel.c:805
 __gre_xmit syzkaller/managers/upstream-kcsan-gce/kernel/net/ipv4/ip_gre.c:466 [inline]
 ipgre_xmit+0x4f5/0x550 syzkaller/managers/upstream-kcsan-gce/kernel/net/ipv4/ip_gre.c:648
 __netdev_start_xmit syzkaller/managers/upstream-kcsan-gce/kernel/./include/linux/netdevice.h:4776 [inline]
 netdev_start_xmit syzkaller/managers/upstream-kcsan-gce/kernel/./include/linux/netdevice.h:4790 [inline]
 xmit_one+0xf9/0x2e0 syzkaller/managers/upstream-kcsan-gce/kernel/net/core/dev.c:3574
 dev_hard_start_xmit syzkaller/managers/upstream-kcsan-gce/kernel/net/core/dev.c:3590 [inline]
 __dev_queue_xmit+0xf22/0x1570 syzkaller/managers/upstream-kcsan-gce/kernel/net/core/dev.c:4151
 dev_queue_xmit+0x13/0x20 syzkaller/managers/upstream-kcsan-gce/kernel/net/core/dev.c:4184
 __bpf_tx_skb syzkaller/managers/upstream-kcsan-gce/kernel/net/core/filter.c:2116 [inline]
 __bpf_redirect_no_mac syzkaller/managers/upstream-kcsan-gce/kernel/net/core/filter.c:2141 [inline]
 __bpf_redirect+0x54f/0x760 syzkaller/managers/upstream-kcsan-gce/kernel/net/core/filter.c:2164
 ____bpf_clone_redirect syzkaller/managers/upstream-kcsan-gce/kernel/net/core/filter.c:2448 [inline]
 bpf_clone_redirect+0x168/0x1c0 syzkaller/managers/upstream-kcsan-gce/kernel/net/core/filter.c:2420
 bpf_prog_bebbfe2050753572+0x56/0x8c
 bpf_dispatcher_nop_func syzkaller/managers/upstream-kcsan-gce/kernel/./include/linux/bpf.h:651 [inline]
 bpf_test_run+0x278/0x460 syzkaller/managers/upstream-kcsan-gce/kernel/net/bpf/test_run.c:50
 bpf_prog_test_run_skb+0x714/0xe90 syzkaller/managers/upstream-kcsan-gce/kernel/net/bpf/test_run.c:582
 bpf_prog_test_run syzkaller/managers/upstream-kcsan-gce/kernel/kernel/bpf/syscall.c:3122 [inline]
 __do_sys_bpf+0x3971/0x9950 syzkaller/managers/upstream-kcsan-gce/kernel/kernel/bpf/syscall.c:4400
 __se_sys_bpf syzkaller/managers/upstream-kcsan-gce/kernel/kernel/bpf/syscall.c:4340 [inline]
 __x64_sys_bpf+0x3d/0x50 syzkaller/managers/upstream-kcsan-gce/kernel/kernel/bpf/syscall.c:4340
 do_syscall_64+0x39/0x80 syzkaller/managers/upstream-kcsan-gce/kernel/arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 25499 Comm: syz-executor.0 Not tainted 5.11.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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