[moderation] [fs?] KCSAN: data-race in ____sys_recvmsg / fasync_insert_entry (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 22a40d14b572 Linux 6.10-rc6
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=134f0e99980000
kernel config: https://syzkaller.appspot.com/x/.config?x=5b9537cd00be479e
dashboard link: https://syzkaller.appspot.com/bug?extid=854f341cab090c873189
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [alex....@gmail.com bra...@kernel.org chuck...@oracle.com ja...@suse.cz jla...@kernel.org linux-...@vger.kernel.org linux-...@vger.kernel.org vi...@zeniv.linux.org.uk]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ebe2f3933faf/disk-22a40d14.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7227032da0fe/vmlinux-22a40d14.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a330dc1e107b/bzImage-22a40d14.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+854f34...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in ____sys_recvmsg / fasync_insert_entry

read-write to 0xffff888100ee0048 of 4 bytes by task 22242 on cpu 1:
fasync_insert_entry+0x124/0x150 fs/fcntl.c:964
fasync_add_entry fs/fcntl.c:991 [inline]
fasync_helper+0x5d/0xc0 fs/fcntl.c:1009
sock_fasync+0x60/0xd0 net/socket.c:1446
setfl fs/fcntl.c:75 [inline]
do_fcntl+0xc0b/0xe20 fs/fcntl.c:375
__do_sys_fcntl fs/fcntl.c:492 [inline]
__se_sys_fcntl+0xc4/0x190 fs/fcntl.c:477
__x64_sys_fcntl+0x43/0x50 fs/fcntl.c:477
x64_sys_call+0x292f/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:73
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888100ee0048 of 4 bytes by task 22237 on cpu 0:
____sys_recvmsg+0xc8/0x280 net/socket.c:2798
___sys_recvmsg net/socket.c:2846 [inline]
do_recvmmsg+0x2eb/0x720 net/socket.c:2940
__sys_recvmmsg net/socket.c:3019 [inline]
__do_sys_recvmmsg net/socket.c:3042 [inline]
__se_sys_recvmmsg net/socket.c:3035 [inline]
__x64_sys_recvmmsg+0xe2/0x170 net/socket.c:3035
x64_sys_call+0x271d/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:300
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000002 -> 0x00002c02

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 22237 Comm: syz.0.5839 Not tainted 6.10.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
==================================================================


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