linux-kernel - [syzbot] [fs?] [mm?] KCSAN: data-race in copy_fs / free

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Message-ID: <681b580b.050a0220.37980e.0405.GAE@google.com>
Date: Wed, 07 May 2025 05:54:35 -0700
From: syzbot <syzbot+2428028ccd7d1ff933a0@...kaller.appspotmail.com>
To: brauner@...nel.org, jack@...e.cz, kees@...nel.org, 
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-mm@...ck.org, syzkaller-bugs@...glegroups.com, viro@...iv.linux.org.uk
Subject: [syzbot] [fs?] [mm?] KCSAN: data-race in copy_fs / free_bprm

Hello,

syzbot found the following issue on:

HEAD commit:    0d8d44db295c Merge tag 'for-6.15-rc5-tag' of git://git.ker..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14e971cc580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=6154604431d9aaf9
dashboard link: https://syzkaller.appspot.com/bug?extid=2428028ccd7d1ff933a0
compiler:       Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d91fa429308f/disk-0d8d44db.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/24f0298ad2f8/vmlinux-0d8d44db.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d805d3a8719f/bzImage-0d8d44db.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2428028ccd7d1ff933a0@...kaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in copy_fs / free_bprm

write to 0xffff88810475a110 of 4 bytes by task 10717 on cpu 0:
 free_bprm+0x122/0x220 fs/exec.c:1498
 do_execveat_common+0x560/0x750 fs/exec.c:1970
 do_execveat fs/exec.c:2053 [inline]
 __do_sys_execveat fs/exec.c:2127 [inline]
 __se_sys_execveat fs/exec.c:2121 [inline]
 __x64_sys_execveat+0x73/0x90 fs/exec.c:2121
 x64_sys_call+0x2dae/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:323
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810475a110 of 4 bytes by task 10715 on cpu 1:
 copy_fs+0x90/0xf0 kernel/fork.c:1804
 copy_process+0xc6e/0x1f90 kernel/fork.c:2420
 kernel_clone+0x16c/0x5b0 kernel/fork.c:2844
 __do_sys_clone3 kernel/fork.c:3148 [inline]
 __se_sys_clone3+0x1c2/0x200 kernel/fork.c:3127
 __x64_sys_clone3+0x31/0x40 kernel/fork.c:3127
 x64_sys_call+0x10c9/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:436
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000001 -> 0x00000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 10715 Comm: syz.5.2513 Not tainted 6.15.0-rc5-syzkaller-00032-g0d8d44db295c #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
==================================================================


---
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