syzbot

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BUG: KCSAN: data-race in iptunnel_xmit / iptunnel_xmit

write to 0xffff8880a13c3140 of 8 bytes by task 18059 on cpu 1:
 iptunnel_xmit_stats include/net/ip_tunnels.h:455 [inline]
 iptunnel_xmit+0x526/0x540 net/ipv4/ip_tunnel_core.c:86
 ip_tunnel_xmit+0x98c/0x13c0 net/ipv4/ip_tunnel.c:814
 __gre_xmit+0x38e/0x4e0 net/ipv4/ip_gre.c:448
 ipgre_xmit+0x337/0x640 net/ipv4/ip_gre.c:632
 __netdev_start_xmit include/linux/netdevice.h:4533 [inline]
 netdev_start_xmit include/linux/netdevice.h:4547 [inline]
 xmit_one net/core/dev.c:3477 [inline]
 dev_hard_start_xmit+0xeb/0x420 net/core/dev.c:3493
 __dev_queue_xmit+0x11f7/0x1810 net/core/dev.c:4052
 dev_queue_xmit+0x1e/0x30 net/core/dev.c:4085
 __bpf_tx_skb net/core/filter.c:2061 [inline]
 __bpf_redirect_common net/core/filter.c:2100 [inline]
 __bpf_redirect+0x4bb/0x710 net/core/filter.c:2107
 ____bpf_clone_redirect net/core/filter.c:2140 [inline]
 bpf_clone_redirect+0x19a/0x1f0 net/core/filter.c:2112
 bpf_prog_bebbfe2050753572+0x5c/0x240
 bpf_dispatcher_nop_func include/linux/bpf.h:545 [inline]
 bpf_test_run+0x250/0x560 net/bpf/test_run.c:49
 bpf_prog_test_run_skb+0x668/0xad0 net/bpf/test_run.c:438
 bpf_prog_test_run kernel/bpf/syscall.c:2771 [inline]
 __do_sys_bpf+0x1c4d/0x3100 kernel/bpf/syscall.c:3721
 __se_sys_bpf kernel/bpf/syscall.c:3661 [inline]
 __x64_sys_bpf+0x47/0x60 kernel/bpf/syscall.c:3661
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880a13c3140 of 8 bytes by task 18058 on cpu 0:
 iptunnel_xmit_stats include/net/ip_tunnels.h:455 [inline]
 iptunnel_xmit+0x513/0x540 net/ipv4/ip_tunnel_core.c:86
 ip_tunnel_xmit+0x98c/0x13c0 net/ipv4/ip_tunnel.c:814
 __gre_xmit+0x38e/0x4e0 net/ipv4/ip_gre.c:448
 ipgre_xmit+0x337/0x640 net/ipv4/ip_gre.c:632
 __netdev_start_xmit include/linux/netdevice.h:4533 [inline]
 netdev_start_xmit include/linux/netdevice.h:4547 [inline]
 xmit_one net/core/dev.c:3477 [inline]
 dev_hard_start_xmit+0xeb/0x420 net/core/dev.c:3493
 __dev_queue_xmit+0x11f7/0x1810 net/core/dev.c:4052
 dev_queue_xmit+0x1e/0x30 net/core/dev.c:4085
 __bpf_tx_skb net/core/filter.c:2061 [inline]
 __bpf_redirect_common net/core/filter.c:2100 [inline]
 __bpf_redirect+0x4bb/0x710 net/core/filter.c:2107
 ____bpf_clone_redirect net/core/filter.c:2140 [inline]
 bpf_clone_redirect+0x19a/0x1f0 net/core/filter.c:2112
 bpf_prog_bebbfe2050753572+0x5c/0x8ac
 bpf_dispatcher_nop_func include/linux/bpf.h:545 [inline]
 bpf_test_run+0x250/0x560 net/bpf/test_run.c:49
 bpf_prog_test_run_skb+0x668/0xad0 net/bpf/test_run.c:438
 bpf_prog_test_run kernel/bpf/syscall.c:2771 [inline]
 __do_sys_bpf+0x1c4d/0x3100 kernel/bpf/syscall.c:3721
 __se_sys_bpf kernel/bpf/syscall.c:3661 [inline]
 __x64_sys_bpf+0x47/0x60 kernel/bpf/syscall.c:3661
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 18058 Comm: syz-executor.5 Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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