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BUG: KCSAN: data-race in inet_send_prepare / sctp_get_port_local

write to 0xffff88810e0af0ce of 2 bytes by task 10672 on cpu 1:
 sctp_get_port_local+0x765/0xab0 net/sctp/socket.c:8318
 sctp_do_bind+0x38d/0x4a0 net/sctp/socket.c:417
 sctp_autobind net/sctp/socket.c:8597 [inline]
 sctp_connect_new_asoc+0x147/0x390 net/sctp/socket.c:1065
 sctp_sendmsg_new_asoc net/sctp/socket.c:1676 [inline]
 sctp_sendmsg+0x10f5/0x1a90 net/sctp/socket.c:1986
 inet_sendmsg+0x5f/0x80 net/ipv4/af_inet.c:821
 sock_sendmsg_nosec net/socket.c:654 [inline]
 sock_sendmsg net/socket.c:674 [inline]
 __sys_sendto+0x2a8/0x370 net/socket.c:1977
 __do_sys_sendto net/socket.c:1989 [inline]
 __se_sys_sendto net/socket.c:1985 [inline]
 __x64_sys_sendto+0x74/0x90 net/socket.c:1985
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88810e0af0ce of 2 bytes by task 10641 on cpu 0:
 inet_send_prepare+0x21/0x210 net/ipv4/af_inet.c:806
 inet_sendmsg+0x29/0x80 net/ipv4/af_inet.c:818
 sock_sendmsg_nosec net/socket.c:654 [inline]
 sock_sendmsg net/socket.c:674 [inline]
 __sys_sendto+0x2a8/0x370 net/socket.c:1977
 __do_sys_sendto net/socket.c:1989 [inline]
 __se_sys_sendto net/socket.c:1985 [inline]
 __x64_sys_sendto+0x74/0x90 net/socket.c:1985
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 10641 Comm: syz-executor.1 Not tainted 5.12.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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