syzbot

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BUG: KCSAN: data-race in ip_tunnel_xmit / ip_tunnel_xmit

write to 0xffff8880b58fd190 of 8 bytes by task 14760 on cpu 0:
 ip_tunnel_xmit+0x12bf/0x13c0 net/ipv4/ip_tunnel.c:756
 __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:4510 [inline]
 netdev_start_xmit include/linux/netdevice.h:4524 [inline]
 xmit_one net/core/dev.c:3470 [inline]
 dev_hard_start_xmit+0xeb/0x420 net/core/dev.c:3486
 __dev_queue_xmit+0x14c4/0x1b80 net/core/dev.c:4063
 dev_queue_xmit+0x1e/0x30 net/core/dev.c:4096
 __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+0xb98/0x1000
 bpf_dispatcher_nopfunc include/linux/bpf.h:521 [inline]
 bpf_test_run+0x250/0x560 net/bpf/test_run.c:48
 bpf_prog_test_run_skb+0x5f6/0xa60 net/bpf/test_run.c:388
 bpf_prog_test_run kernel/bpf/syscall.c:2572 [inline]
 __do_sys_bpf+0xa0e/0x29c0 kernel/bpf/syscall.c:3414
 __se_sys_bpf kernel/bpf/syscall.c:3355 [inline]
 __x64_sys_bpf+0x47/0x60 kernel/bpf/syscall.c:3355
 do_syscall_64+0xc7/0x390 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880b58fd190 of 8 bytes by task 14755 on cpu 1:
 ip_tunnel_xmit+0x12ac/0x13c0 net/ipv4/ip_tunnel.c:756
 __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:4510 [inline]
 netdev_start_xmit include/linux/netdevice.h:4524 [inline]
 xmit_one net/core/dev.c:3470 [inline]
 dev_hard_start_xmit+0xeb/0x420 net/core/dev.c:3486
 __dev_queue_xmit+0x14c4/0x1b80 net/core/dev.c:4063
 dev_queue_xmit+0x1e/0x30 net/core/dev.c:4096
 __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+0x7b8/0x1000
 bpf_dispatcher_nopfunc include/linux/bpf.h:521 [inline]
 bpf_test_run+0x250/0x560 net/bpf/test_run.c:48
 bpf_prog_test_run_skb+0x5f6/0xa60 net/bpf/test_run.c:388
 bpf_prog_test_run kernel/bpf/syscall.c:2572 [inline]
 __do_sys_bpf+0xa0e/0x29c0 kernel/bpf/syscall.c:3414
 __se_sys_bpf kernel/bpf/syscall.c:3355 [inline]
 __x64_sys_bpf+0x47/0x60 kernel/bpf/syscall.c:3355
 do_syscall_64+0xc7/0x390 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 14755 Comm: syz-executor.1 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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