syzbot

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BUG: KCSAN: data-race in sctp_association_free / sctp_wait_for_connect

write to 0xffff8880aa6ec01c of 1 bytes by task 16849 on cpu 1:
 sctp_association_free+0x101/0x480 net/sctp/associola.c:336
 sctp_cmd_delete_tcb net/sctp/sm_sideeffect.c:930 [inline]
 sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1318 [inline]
 sctp_side_effects net/sctp/sm_sideeffect.c:1185 [inline]
 sctp_do_sm+0x2857/0x2fd0 net/sctp/sm_sideeffect.c:1156
 sctp_primitive_SHUTDOWN+0x7b/0xa0 net/sctp/primitive.c:89
 sctp_close+0x2a2/0x5e0 net/sctp/socket.c:1514
 inet_release+0x86/0x100 net/ipv4/af_inet.c:427
 __sock_release+0x85/0x160 net/socket.c:605
 sock_close+0x24/0x30 net/socket.c:1283
 __fput+0x1e1/0x520 fs/file_table.c:280
 ____fput+0x1f/0x30 fs/file_table.c:313
 task_work_run+0xf6/0x130 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x2b4/0x2c0 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:278 [inline]
 do_syscall_64+0x384/0x3a0 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880aa6ec01c of 1 bytes by task 16845 on cpu 0:
 sctp_wait_for_connect+0x19d/0x330 net/sctp/socket.c:9269
 sctp_sendmsg_to_asoc+0x13c3/0x1420 net/sctp/socket.c:1870
 sctp_sendmsg+0xbeb/0x14f0 net/sctp/socket.c:2016
 inet_sendmsg+0x6d/0x90 net/ipv4/af_inet.c:807
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0x9f/0xc0 net/socket.c:672
 __sys_sendto+0x21f/0x320 net/socket.c:1998
 __do_sys_sendto net/socket.c:2010 [inline]
 __se_sys_sendto net/socket.c:2006 [inline]
 __x64_sys_sendto+0x89/0xb0 net/socket.c:2006
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 16845 Comm: syz-executor.3 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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