KCSAN: data-race in __skb_wait_for_more_packets / unix_release_sock (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: bf3e7628 Merge branch 'mtd/fixes' of git://git.kernel.org/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16c9b4b2500000
kernel config: https://syzkaller.appspot.com/x/.config?x=76dfc991796328d4
dashboard link: https://syzkaller.appspot.com/bug?extid=f92e715394712bc0ad01
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project.git 913f6005669cfb590c99865a90bc51ed0983d09d)
CC: [da...@davemloft.net ktk...@virtuozzo.com ku...@kernel.org linux-...@vger.kernel.org net...@vger.kernel.org pab...@redhat.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+f92e71...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __skb_wait_for_more_packets / unix_release_sock

write to 0xffff88812f95226a of 1 bytes by task 855 on cpu 0:
unix_release_sock+0x25e/0x650 net/unix/af_unix.c:548
unix_release+0x2f/0x50 net/unix/af_unix.c:859
__sock_release net/socket.c:596 [inline]
sock_close+0x6c/0x150 net/socket.c:1277
__fput+0x243/0x4d0 fs/file_table.c:281
____fput+0x11/0x20 fs/file_table.c:314
task_work_run+0x8e/0x110 kernel/task_work.c:151
get_signal+0x3eb/0x1510 kernel/signal.c:2562
arch_do_signal+0x25/0x260 arch/x86/kernel/signal.c:811
exit_to_user_mode_loop kernel/entry/common.c:161 [inline]
exit_to_user_mode_prepare+0xde/0x170 kernel/entry/common.c:191
syscall_exit_to_user_mode+0x16/0x30 kernel/entry/common.c:266
do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88812f95226a of 1 bytes by task 859 on cpu 1:
__skb_wait_for_more_packets+0xe0/0x2a0 net/core/datagram.c:106
unix_dgram_recvmsg+0x1d2/0x840 net/unix/af_unix.c:2112
unix_seqpacket_recvmsg+0x5a/0x70 net/unix/af_unix.c:2065
sock_recvmsg_nosec net/socket.c:885 [inline]
sock_recvmsg net/socket.c:903 [inline]
sock_read_iter+0x19e/0x1e0 net/socket.c:976
call_read_iter include/linux/fs.h:1881 [inline]
generic_file_splice_read+0x22a/0x310 fs/splice.c:311
sock_splice_read+0xa5/0xb0 net/socket.c:954
do_splice_to fs/splice.c:788 [inline]
do_splice+0xcf8/0xf30 fs/splice.c:1093
__do_splice fs/splice.c:1137 [inline]
__do_sys_splice fs/splice.c:1343 [inline]
__se_sys_splice+0x2a6/0x390 fs/splice.c:1325
__x64_sys_splice+0x74/0x80 fs/splice.c:1325
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: 859 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.