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BUG: KCSAN: data-race in inet_send_prepare / sctp_get_port_local

write to 0xffff88801f42b3ce of 2 bytes by task 27834 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_bind+0x6a/0x80 net/sctp/socket.c:317
 inet6_bind+0x6a/0x160 net/ipv6/af_inet6.c:448
 __sys_bind+0x200/0x290 net/socket.c:1637
 __do_sys_bind net/socket.c:1648 [inline]
 __se_sys_bind net/socket.c:1646 [inline]
 __x64_sys_bind+0x3d/0x50 net/socket.c:1646
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88801f42b3ce of 2 bytes by task 27841 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: 27841 Comm: syz-executor.4 Not tainted 5.12.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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