KCSAN: data-race in __ip6_datagram_connect / udpv6_sendmsg (6)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 7fef2edf7cc7 sd: don't mess with SD_MINORS for CONFIG_DEBU..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10582cd2300000
kernel config: https://syzkaller.appspot.com/x/.config?x=f5e73542d774430b
dashboard link: https://syzkaller.appspot.com/bug?extid=da82dc781cabb1cd5b9f
compiler: Debian clang version 11.0.1-2
CC: [da...@davemloft.net dsa...@kernel.org ku...@kernel.org linux-...@vger.kernel.org net...@vger.kernel.org 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+da82dc...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __ip6_datagram_connect / udpv6_sendmsg

write to 0xffff888107c645c0 of 4 bytes by task 15456 on cpu 1:
__ipv6_addr_set_half include/net/ipv6.h:561 [inline]
ipv6_addr_set include/net/ipv6.h:570 [inline]
ipv6_addr_set_v4mapped include/net/ipv6.h:738 [inline]
__ip6_datagram_connect+0x19f/0x840 net/ipv6/datagram.c:197
ip6_datagram_connect+0x2a/0x40 net/ipv6/datagram.c:272
inet_dgram_connect+0x107/0x190 net/ipv4/af_inet.c:580
__sys_connect_file net/socket.c:1872 [inline]
__sys_connect+0x245/0x280 net/socket.c:1889
__do_sys_connect net/socket.c:1899 [inline]
__se_sys_connect net/socket.c:1896 [inline]
__x64_sys_connect+0x3d/0x50 net/socket.c:1896
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888107c645c0 of 4 bytes by task 15470 on cpu 0:
ipv6_addr_v4mapped include/net/ipv6.h:696 [inline]
udpv6_sendmsg+0x2c1/0x16b0 net/ipv6/udp.c:1336
inet6_sendmsg+0x5f/0x80 net/ipv6/af_inet6.c:642
sock_sendmsg_nosec net/socket.c:702 [inline]
sock_sendmsg net/socket.c:722 [inline]
____sys_sendmsg+0x360/0x4d0 net/socket.c:2385
___sys_sendmsg net/socket.c:2439 [inline]
__sys_sendmmsg+0x315/0x4b0 net/socket.c:2525
__do_sys_sendmmsg net/socket.c:2554 [inline]
__se_sys_sendmmsg net/socket.c:2551 [inline]
__x64_sys_sendmmsg+0x53/0x60 net/socket.c:2551
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000000 -> 0xffff0000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 15470 Comm: syz-executor.0 Not tainted 5.14.0-rc1-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.