KCSAN: data-race in inet_send_prepare / sctp_get_port_local (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 7059c2c0 Merge branch 'for-linus' of git://git.kernel.org/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14c11527500000
kernel config: https://syzkaller.appspot.com/x/.config?x=c949fed53798f819
dashboard link: https://syzkaller.appspot.com/bug?extid=f4466d64824a0cfab290
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project.git 913f6005669cfb590c99865a90bc51ed0983d09d)
CC: [da...@davemloft.net ku...@kernel.org linux-...@vger.kernel.org linux...@vger.kernel.org marcelo...@gmail.com net...@vger.kernel.org nho...@tuxdriver.com vyas...@gmail.com]

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f4466d...@syzkaller.appspotmail.com

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

write to 0xffff8880145e9a0e of 2 bytes by task 21579 on cpu 0:
sctp_get_port_local+0x73f/0xa80 net/sctp/socket.c:8202
sctp_do_bind+0x38d/0x4a0 net/sctp/socket.c:417
sctp_autobind net/sctp/socket.c:8481 [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:651 [inline]
sock_sendmsg net/socket.c:671 [inline]
__sys_sendto+0x2ae/0x380 net/socket.c:1992
__do_sys_sendto net/socket.c:2004 [inline]
__se_sys_sendto net/socket.c:2000 [inline]
__x64_sys_sendto+0x74/0x90 net/socket.c:2000
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880145e9a0e of 2 bytes by task 21595 on cpu 1:
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:651 [inline]
sock_sendmsg net/socket.c:671 [inline]
__sys_sendto+0x2ae/0x380 net/socket.c:1992
__do_sys_sendto net/socket.c:2004 [inline]
__se_sys_sendto net/socket.c:2000 [inline]
__x64_sys_sendto+0x74/0x90 net/socket.c:2000
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: 1 PID: 21595 Comm: syz-executor.0 Not tainted 5.10.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.