syzbot

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BUG: KCSAN: data-race in __dev_open / ip_route_output_key_hash_rcu

read to 0xffff888152adb0a0 of 4 bytes by task 10819 on cpu 1:
 ip_route_output_key_hash_rcu+0x17e/0x12b0 net/ipv4/route.c:2721
 ip_route_output_key_hash net/ipv4/route.c:2644 [inline]
 __ip_route_output_key include/net/route.h:134 [inline]
 ip_route_output_flow+0xa6/0x150 net/ipv4/route.c:2872
 udp_sendmsg+0xe7c/0x1310 net/ipv4/udp.c:1216
 udpv6_sendmsg+0x76d/0x1540 net/ipv6/udp.c:1390
 inet6_sendmsg+0x63/0x80 net/ipv6/af_inet6.c:660
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x37c/0x4d0 net/socket.c:2584
 ___sys_sendmsg net/socket.c:2638 [inline]
 __sys_sendmmsg+0x269/0x500 net/socket.c:2724
 __do_sys_sendmmsg net/socket.c:2753 [inline]
 __se_sys_sendmmsg net/socket.c:2750 [inline]
 __x64_sys_sendmmsg+0x57/0x60 net/socket.c:2750
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read-write to 0xffff888152adb0a0 of 4 bytes by task 10818 on cpu 0:
 __dev_open+0x241/0x2e0 net/core/dev.c:1453
 __dev_change_flags+0x153/0x410 net/core/dev.c:8648
 rtnl_configure_link net/core/rtnetlink.c:3326 [inline]
 rtnl_newlink_create net/core/rtnetlink.c:3523 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3735 [inline]
 rtnl_newlink+0x120e/0x1670 net/core/rtnetlink.c:3748
 rtnetlink_rcv_msg+0x80a/0x8c0 net/core/rtnetlink.c:6615
 netlink_rcv_skb+0x126/0x220 net/netlink/af_netlink.c:2543
 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:6633
 netlink_unicast_kernel net/netlink/af_netlink.c:1341 [inline]
 netlink_unicast+0x589/0x660 net/netlink/af_netlink.c:1367
 netlink_sendmsg+0x66e/0x770 net/netlink/af_netlink.c:1908
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x37c/0x4d0 net/socket.c:2584
 ___sys_sendmsg net/socket.c:2638 [inline]
 __sys_sendmsg+0x1e9/0x270 net/socket.c:2667
 __do_sys_sendmsg net/socket.c:2676 [inline]
 __se_sys_sendmsg net/socket.c:2674 [inline]
 __x64_sys_sendmsg+0x46/0x50 net/socket.c:2674
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 10818 Comm: syz-executor.4 Not tainted 6.8.0-rc2-syzkaller-00055-g6764c317b6bb #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
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