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BUG: KCSAN: data-race in prandom_seed / prandom_u32

write to 0xffff888237c28858 of 8 bytes by task 29 on cpu 0:
 siprand_u32 lib/random32.c:372 [inline]
 prandom_u32+0x12f/0x190 lib/random32.c:387
 prandom_u32_max include/linux/prandom.h:96 [inline]
 ip_idents_reserve net/ipv4/route.c:474 [inline]
 __ip_select_ident+0x12d/0x190 net/ipv4/route.c:496
 iptunnel_xmit+0x2f6/0x490 net/ipv4/ip_tunnel_core.c:80
 udp_tunnel_xmit_skb+0x15d/0x170 net/ipv4/udp_tunnel_core.c:171
 geneve_xmit_skb drivers/net/geneve.c:989 [inline]
 geneve_xmit+0x13e5/0x1950 drivers/net/geneve.c:1101
 __netdev_start_xmit include/linux/netdevice.h:4775 [inline]
 netdev_start_xmit include/linux/netdevice.h:4789 [inline]
 xmit_one+0x105/0x2f0 net/core/dev.c:3532
 dev_hard_start_xmit+0x72/0x120 net/core/dev.c:3548
 __dev_queue_xmit+0x84c/0xef0 net/core/dev.c:4176
 dev_queue_xmit+0x13/0x20 net/core/dev.c:4209
 neigh_resolve_output+0x3f0/0x430 net/core/neighbour.c:1528
 neigh_output include/net/neighbour.h:549 [inline]
 ip6_finish_output2+0xa00/0xc20 net/ipv6/ip6_output.c:126
 __ip6_finish_output net/ipv6/ip6_output.c:191 [inline]
 ip6_finish_output+0x446/0x4c0 net/ipv6/ip6_output.c:201
 NF_HOOK_COND include/linux/netfilter.h:296 [inline]
 ip6_output+0x10e/0x210 net/ipv6/ip6_output.c:224
 dst_output include/net/dst.h:451 [inline]
 NF_HOOK include/linux/netfilter.h:307 [inline]
 mld_sendpack+0x3bc/0x580 net/ipv6/mcast.c:1818
 mld_send_cr net/ipv6/mcast.c:2119 [inline]
 mld_ifc_work+0x576/0x800 net/ipv6/mcast.c:2651
 process_one_work+0x3d3/0x720 kernel/workqueue.c:2289
 worker_thread+0x618/0xa70 kernel/workqueue.c:2436
 kthread+0x1a9/0x1e0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30

read to 0xffff888237c28858 of 8 bytes by task 1818 on cpu 1:
 prandom_seed+0xeb/0x270 lib/random32.c:440
 __inet_insert_ifa+0x3a6/0x600 net/ipv4/devinet.c:540
 inet_rtm_newaddr+0x854/0xb40 net/ipv4/devinet.c:962
 rtnetlink_rcv_msg+0x74f/0x7e0 net/core/rtnetlink.c:5993
 netlink_rcv_skb+0x13e/0x240 net/netlink/af_netlink.c:2503
 rtnetlink_rcv+0x18/0x20 net/core/rtnetlink.c:6011
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0x58a/0x660 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x661/0x750 net/netlink/af_netlink.c:1921
 sock_sendmsg_nosec net/socket.c:705 [inline]
 sock_sendmsg net/socket.c:725 [inline]
 __sys_sendto+0x21e/0x2c0 net/socket.c:2040
 __do_sys_sendto net/socket.c:2052 [inline]
 __se_sys_sendto net/socket.c:2048 [inline]
 __x64_sys_sendto+0x74/0x90 net/socket.c:2048
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0xa94a4fbc8a9f3555 -> 0x6c9fef34ed4585c8

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 1818 Comm: syz-executor.3 Not tainted 5.18.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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