syzbot

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BUG: KCSAN: data-race in dccp_connect / dccp_sendmsg

write to 0xffff88812c3dea4c of 4 bytes by task 16460 on cpu 1:
 dccp_sync_mss net/dccp/output.c:190 [inline]
 dccp_connect+0x17f/0x400 net/dccp/output.c:551
 dccp_v4_connect+0x825/0x8a0 net/dccp/ipv4.c:129
 __inet_stream_connect+0x156/0x6e0 net/ipv4/af_inet.c:660
 inet_stream_connect+0x44/0x70 net/ipv4/af_inet.c:724
 __sys_connect_file net/socket.c:1896 [inline]
 __sys_connect+0x197/0x1b0 net/socket.c:1913
 __do_sys_connect net/socket.c:1923 [inline]
 __se_sys_connect net/socket.c:1920 [inline]
 __x64_sys_connect+0x3d/0x50 net/socket.c:1920
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88812c3dea4c of 4 bytes by task 16466 on cpu 0:
 dccp_sendmsg+0x6f/0x6d0 net/dccp/proto.c:745
 inet_sendmsg+0x5f/0x80 net/ipv4/af_inet.c:819
 sock_sendmsg_nosec net/socket.c:704 [inline]
 sock_sendmsg net/socket.c:724 [inline]
 ____sys_sendmsg+0x39a/0x510 net/socket.c:2409
 ___sys_sendmsg net/socket.c:2463 [inline]
 __sys_sendmmsg+0x267/0x4c0 net/socket.c:2549
 __do_sys_sendmmsg net/socket.c:2578 [inline]
 __se_sys_sendmmsg net/socket.c:2575 [inline]
 __x64_sys_sendmmsg+0x53/0x60 net/socket.c:2575
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000218 -> 0x0000ffc3

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 16466 Comm: syz-executor.4 Not tainted 5.16.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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