KCSAN: data-race in inet_send_prepare / sctp_get_port

KCSAN: data-race in inet_send_prepare / sctp_get_port_local (4)
Status: auto-closed as invalid on 2021/02/16 22:07
Reported-by: syzbot+f4466d64824a0cfab290@syzkaller.appspotmail.com
First crash: 231d, last: 193d

similar bugs (4):
Kernel	Title	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in inet_send_prepare / sctp_get_port_local	1	616d	616d	0/22	auto-closed as invalid on 2020/01/26 16:46
upstream	KCSAN: data-race in inet_send_prepare / sctp_get_port_local (3)	2	311d	342d	0/22	auto-closed as invalid on 2020/10/22 02:42
upstream	KCSAN: data-race in inet_send_prepare / sctp_get_port_local (2)	1	390d	390d	0/22	auto-closed as invalid on 2020/08/04 21:16
upstream	KCSAN: data-race in inet_send_prepare / sctp_get_port_local (5)	3	103d	144d	0/22	auto-closed as invalid on 2021/05/18 14:42

Sample crash report:

==================================================================
BUG: KCSAN: data-race in inet_send_prepare / sctp_get_port_local

write to 0xffff888024c305ce of 2 bytes by task 11614 on cpu 1:
 sctp_get_port_local+0x73f/0xa80 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:817
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg net/socket.c:672 [inline]
 ____sys_sendmsg+0x352/0x4c0 net/socket.c:2345
 ___sys_sendmsg net/socket.c:2399 [inline]
 __sys_sendmmsg+0x335/0x4b0 net/socket.c:2489
 __do_sys_sendmmsg net/socket.c:2518 [inline]
 __se_sys_sendmmsg net/socket.c:2515 [inline]
 __x64_sys_sendmmsg+0x53/0x60 net/socket.c:2515
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888024c305ce of 2 bytes by task 11613 on cpu 0:
 inet_send_prepare+0x21/0x210 net/ipv4/af_inet.c:802
 inet_sendmsg+0x29/0x80 net/ipv4/af_inet.c:814
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg net/socket.c:672 [inline]
 ____sys_sendmsg+0x352/0x4c0 net/socket.c:2345
 ___sys_sendmsg net/socket.c:2399 [inline]
 __sys_sendmmsg+0x335/0x4b0 net/socket.c:2489
 __do_sys_sendmmsg net/socket.c:2518 [inline]
 __se_sys_sendmmsg net/socket.c:2515 [inline]
 __x64_sys_sendmmsg+0x53/0x60 net/socket.c:2515
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 11613 Comm: syz-executor.3 Not tainted 5.11.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (3):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info
ci2-upstream-kcsan-gce	2021/01/12 22:06	upstream	e609571b5ffa	0cdd6185	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/11 13:28	upstream	33dc9614dc20	ba24ffcd	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/06 09:44	upstream	7059c2c00a21	f12ba0c5	.config	log	report	info