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BUG: KCSAN: data-race in inet_send_prepare / sctp_get_port_local

write to 0xffff8880a94de10e of 2 bytes by task 15928 on cpu 0:
 sctp_get_port_local+0x73f/0xa80 net/sctp/socket.c:8440
 sctp_do_bind+0x38d/0x4a0 net/sctp/socket.c:417
 sctp_autobind net/sctp/socket.c:8722 [inline]
 sctp_connect_new_asoc+0x14d/0x390 net/sctp/socket.c:1082
 sctp_sendmsg_new_asoc net/sctp/socket.c:1701 [inline]
 sctp_sendmsg+0x10f5/0x1a90 net/sctp/socket.c:2011
 inet_sendmsg+0x5f/0x80 net/ipv4/af_inet.c:814
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg net/socket.c:672 [inline]
 __sys_sendto+0x2ad/0x380 net/socket.c:1995
 __do_sys_sendto net/socket.c:2007 [inline]
 __se_sys_sendto net/socket.c:2003 [inline]
 __x64_sys_sendto+0x74/0x90 net/socket.c:2003
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880a94de10e of 2 bytes by task 15933 on cpu 1:
 inet_send_prepare+0x21/0x210 net/ipv4/af_inet.c:799
 inet_sendmsg+0x29/0x80 net/ipv4/af_inet.c:811
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg net/socket.c:672 [inline]
 __sys_sendto+0x2ad/0x380 net/socket.c:1995
 __do_sys_sendto net/socket.c:2007 [inline]
 __se_sys_sendto net/socket.c:2003 [inline]
 __x64_sys_sendto+0x74/0x90 net/socket.c:2003
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 15933 Comm: syz-executor.1 Not tainted 5.8.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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