==================================================================
BUG: KCSAN: data-race in del_timer / enqueue_timer

write to 0xffff8880a200f190 of 8 bytes by task 22737 on cpu 0:
 hlist_add_head include/linux/list.h:787 [inline]
 enqueue_timer+0x6c/0x210 kernel/time/timer.c:540
 __internal_add_timer+0x4f/0x60 kernel/time/timer.c:553
 internal_add_timer kernel/time/timer.c:595 [inline]
 __mod_timer kernel/time/timer.c:1053 [inline]
 mod_timer kernel/time/timer.c:1100 [inline]
 add_timer+0x250/0x550 kernel/time/timer.c:1136
 sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1522 [inline]
 sctp_side_effects net/sctp/sm_sideeffect.c:1184 [inline]
 sctp_do_sm+0x1f9e/0x2ef0 net/sctp/sm_sideeffect.c:1155
 sctp_primitive_SHUTDOWN+0x7b/0xa0 net/sctp/primitive.c:89
 sctp_close+0x28f/0x500 net/sctp/socket.c:1515
 inet_release+0x86/0x100 net/ipv4/af_inet.c:427
 inet6_release+0x4a/0x70 net/ipv6/af_inet6.c:470
 __sock_release+0x85/0x160 net/socket.c:590
 sock_close+0x24/0x30 net/socket.c:1268
 __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:163
 prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
 do_syscall_64+0x353/0x370 arch/x86/entry/common.c:300
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880a200f190 of 8 bytes by task 22742 on cpu 1:
 del_timer+0x3b/0xb0 kernel/time/timer.c:1198
 sctp_cmd_hb_timers_stop net/sctp/sm_sideeffect.c:698 [inline]
 sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1653 [inline]
 sctp_side_effects net/sctp/sm_sideeffect.c:1184 [inline]
 sctp_do_sm+0x5e7/0x2ef0 net/sctp/sm_sideeffect.c:1155
 sctp_primitive_SHUTDOWN+0x7b/0xa0 net/sctp/primitive.c:89
 sctp_close+0x28f/0x500 net/sctp/socket.c:1515
 inet_release+0x86/0x100 net/ipv4/af_inet.c:427
 inet6_release+0x4a/0x70 net/ipv6/af_inet6.c:470
 __sock_release+0x85/0x160 net/socket.c:590
 sock_close+0x24/0x30 net/socket.c:1268
 __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:163
 prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
 do_syscall_64+0x353/0x370 arch/x86/entry/common.c:300
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 22742 Comm: syz-executor.5 Not tainted 5.4.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================