syzbot

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BUG: KCSAN: data-race in dccp_connect / dccp_sendmsg

write to 0xffff8880165fe83c of 4 bytes by task 23129 on cpu 0:
 dccp_sync_mss net/dccp/output.c:188 [inline]
 dccp_connect+0x17f/0x3e0 net/dccp/output.c:542
 dccp_v4_connect+0x817/0x890 net/dccp/ipv4.c:122
 __inet_stream_connect+0x586/0x690 net/ipv4/af_inet.c:661
 inet_stream_connect+0x44/0x70 net/ipv4/af_inet.c:725
 __sys_connect_file net/socket.c:1852 [inline]
 __sys_connect+0x245/0x280 net/socket.c:1869
 __do_sys_connect net/socket.c:1879 [inline]
 __se_sys_connect net/socket.c:1876 [inline]
 __x64_sys_connect+0x3d/0x50 net/socket.c:1876
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880165fe83c of 4 bytes by task 23134 on cpu 1:
 dccp_sendmsg+0x4a/0x690 net/dccp/proto.c:745
 inet_sendmsg+0x5f/0x80 net/ipv4/af_inet.c:817
 sock_sendmsg_nosec net/socket.c:651 [inline]
 sock_sendmsg net/socket.c:671 [inline]
 ____sys_sendmsg+0x352/0x4c0 net/socket.c:2353
 ___sys_sendmsg net/socket.c:2407 [inline]
 __sys_sendmmsg+0x335/0x4b0 net/socket.c:2497
 __do_sys_sendmmsg net/socket.c:2526 [inline]
 __se_sys_sendmmsg net/socket.c:2523 [inline]
 __x64_sys_sendmmsg+0x53/0x60 net/socket.c:2523
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 23134 Comm: syz-executor.0 Not tainted 5.9.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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