syzbot

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BUG: KCSAN: data-race in udpv6_sendmsg / udpv6_sendmsg

write to 0xffff888139b9ce68 of 4 bytes by task 4293 on cpu 0:
 udpv6_sendmsg+0x13f1/0x1500 net/ipv6/udp.c:1606
 inet6_sendmsg+0x63/0x80 net/ipv6/af_inet6.c:651
 sock_sendmsg_nosec net/socket.c:724 [inline]
 sock_sendmsg net/socket.c:747 [inline]
 __sys_sendto+0x246/0x300 net/socket.c:2144
 __do_sys_sendto net/socket.c:2156 [inline]
 __se_sys_sendto net/socket.c:2152 [inline]
 __x64_sys_sendto+0x78/0x90 net/socket.c:2152
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff888139b9ce68 of 4 bytes by task 4292 on cpu 1:
 udpv6_sendmsg+0x5af/0x1500 net/ipv6/udp.c:1415
 inet6_sendmsg+0x63/0x80 net/ipv6/af_inet6.c:651
 sock_sendmsg_nosec net/socket.c:724 [inline]
 sock_sendmsg net/socket.c:747 [inline]
 ____sys_sendmsg+0x375/0x4c0 net/socket.c:2503
 ___sys_sendmsg net/socket.c:2557 [inline]
 __sys_sendmmsg+0x263/0x500 net/socket.c:2643
 __do_sys_sendmmsg net/socket.c:2672 [inline]
 __se_sys_sendmmsg net/socket.c:2669 [inline]
 __x64_sys_sendmmsg+0x57/0x60 net/socket.c:2669
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00000000 -> 0x0000000a

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 4292 Comm: syz-executor.1 Not tainted 6.4.0-rc2-syzkaller-00338-ge2065b8c1b01 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/28/2023
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