KCSAN: data-race in inet_dgram_connect / udp_lib_get_port (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4ef8451b Merge tag 'perf-tools-for-v5.10-2020-11-03' of gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=137ab4b2500000
kernel config: https://syzkaller.appspot.com/x/.config?x=76dfc991796328d4
dashboard link: https://syzkaller.appspot.com/bug?extid=1ef3934652a5b805dfce
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project.git 913f6005669cfb590c99865a90bc51ed0983d09d)
CC: [and...@kernel.org a...@kernel.org b...@vger.kernel.org dan...@iogearbox.net da...@davemloft.net john.fa...@gmail.com ka...@fb.com kps...@chromium.org ku...@kernel.org kuz...@ms2.inr.ac.ru linux-...@vger.kernel.org net...@vger.kernel.org songliu...@fb.com y...@fb.com yosh...@linux-ipv6.org]

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+1ef393...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in inet_dgram_connect / udp_lib_get_port

write to 0xffff88803bc7aa8e of 2 bytes by task 11969 on cpu 1:
udp_lib_get_port+0x4ad/0xdb0 net/ipv4/udp.c:308
udp_v6_get_port+0x5e/0x70 net/ipv6/udp.c:89
inet_autobind net/ipv4/af_inet.c:183 [inline]
inet_send_prepare+0xd0/0x210 net/ipv4/af_inet.c:803
inet6_sendmsg+0x29/0x80 net/ipv6/af_inet6.c:635
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 0xffff88803bc7aa8e of 2 bytes by task 11963 on cpu 0:
inet_dgram_connect+0xa5/0x200 net/ipv4/af_inet.c:575
__sys_connect_file net/socket.c:1852 [inline]
__sys_connect+0x245/0x280 net/socket.c:1869
__do_sys_connect net/socket.c:1879 [inline]
__se_sys_connect net/socket.c:1876 [inline]
__x64_sys_connect+0x3d/0x50 net/socket.c:1876
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: 11963 Comm: syz-executor.2 Not tainted 5.10.0-rc2-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.