syzbot

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BUG: KCSAN: data-race in __ip4_datagram_connect / __ip_make_skb

read to 0xffff88818ce8085a of 2 bytes by task 29333 on cpu 0:
 ip_select_ident_segs include/net/ip.h:532 [inline]
 ip_select_ident include/net/ip.h:547 [inline]
 __ip_make_skb+0x83a/0xb50 net/ipv4/ip_output.c:1559
 ip_make_skb+0x238/0x2c0 net/ipv4/ip_output.c:1663
 udp_sendmsg+0x1121/0x1200 net/ipv4/udp.c:1251
 udpv6_sendmsg+0x64e/0x14a0
 inet6_sendmsg+0x5f/0x80 net/ipv6/af_inet6.c:653
 sock_sendmsg_nosec net/socket.c:714 [inline]
 sock_sendmsg net/socket.c:734 [inline]
 ____sys_sendmsg+0x38f/0x500 net/socket.c:2482
 ___sys_sendmsg net/socket.c:2536 [inline]
 __sys_sendmmsg+0x27c/0x4a0 net/socket.c:2622
 __do_sys_sendmmsg net/socket.c:2651 [inline]
 __se_sys_sendmmsg net/socket.c:2648 [inline]
 __x64_sys_sendmmsg+0x53/0x60 net/socket.c:2648
 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+0x63/0xcd

write to 0xffff88818ce8085a of 2 bytes by task 29334 on cpu 1:
 __ip4_datagram_connect+0x752/0x7b0 net/ipv4/datagram.c:74
 __ip6_datagram_connect+0x562/0x7d0 net/ipv6/datagram.c:189
 ip6_datagram_connect+0x2a/0x40 net/ipv6/datagram.c:272
 inet_dgram_connect+0x107/0x190 net/ipv4/af_inet.c:576
 __sys_connect_file net/socket.c:1976 [inline]
 __sys_connect+0x197/0x1b0 net/socket.c:1993
 __do_sys_connect net/socket.c:2003 [inline]
 __se_sys_connect net/socket.c:2000 [inline]
 __x64_sys_connect+0x3d/0x50 net/socket.c:2000
 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+0x63/0xcd

value changed: 0x2fc2 -> 0x2fc3

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 29334 Comm: syz-executor.1 Not tainted 6.0.0-rc3-syzkaller-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
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