linux-kernel - [syzbot] [kernel?] KCSAN: data-race in do_timer_create / do_timer

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Message-ID: <000000000000a3723305f9d98fc3@google.com>
Date:   Fri, 21 Apr 2023 07:34:56 -0700
From:   syzbot <syzbot+5c54bd3eb218bb595aa9@...kaller.appspotmail.com>
To:     linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com,
        tglx@...utronix.de
Subject: [syzbot] [kernel?] KCSAN: data-race in do_timer_create /
 do_timer_create (8)

Hello,

syzbot found the following issue on:

HEAD commit:    6a8f57ae2eb0 Linux 6.3-rc7
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=154fe6c0280000
kernel config:  https://syzkaller.appspot.com/x/.config?x=fa4baf7c6b35b5d5
dashboard link: https://syzkaller.appspot.com/bug?extid=5c54bd3eb218bb595aa9
compiler:       Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/fd87c4c006cf/disk-6a8f57ae.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2ac4347e9165/vmlinux-6a8f57ae.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e5844a1e58ba/bzImage-6a8f57ae.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5c54bd3eb218bb595aa9@...kaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in do_timer_create / do_timer_create

write to 0xffff888100ea9bc4 of 4 bytes by task 7660 on cpu 1:
 do_timer_create+0x2fd/0xa30 kernel/time/posix-timers.c:516
 __se_sys_timer_create kernel/time/posix-timers.c:577 [inline]
 __x64_sys_timer_create+0xbb/0xe0 kernel/time/posix-timers.c:577
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff888100ea9bc4 of 4 bytes by task 7659 on cpu 0:
 posix_timer_add kernel/time/posix-timers.c:143 [inline]
 do_timer_create+0x19f/0xa30 kernel/time/posix-timers.c:516
 __se_sys_timer_create kernel/time/posix-timers.c:577 [inline]
 __x64_sys_timer_create+0xbb/0xe0 kernel/time/posix-timers.c:577
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00000018 -> 0x00000026

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 7659 Comm: syz-executor.1 Not tainted 6.3.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/30/2023
==================================================================


---
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