[moderation] [mm?] [fs?] KCSAN: data-race in copy_fs / free_bprm (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c2f2b01b74be Merge tag 'i3c/for-6.19' of git://git.kernel...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=107c9992580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c3201432211be40f
dashboard link: https://syzkaller.appspot.com/bug?extid=7b74f290c756a4300d71
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
CC: [bra...@kernel.org ja...@suse.cz ke...@kernel.org linux-...@vger.kernel.org linux-...@vger.kernel.org linu...@kvack.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/15a5e839a554/disk-c2f2b01b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/038ca01b3a1e/vmlinux-c2f2b01b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1b489de2e6a0/bzImage-c2f2b01b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7b74f2...@syzkaller.appspotmail.com

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

write to 0xffff888104fa4410 of 4 bytes by task 14168 on cpu 0:
free_bprm+0x122/0x220 fs/exec.c:1389
do_execveat_common+0x560/0x750 fs/exec.c:1861
do_execveat fs/exec.c:1944 [inline]
__do_sys_execveat fs/exec.c:2018 [inline]
__se_sys_execveat fs/exec.c:2012 [inline]
__x64_sys_execveat+0x73/0x90 fs/exec.c:2012
x64_sys_call+0x1c0e/0x3000 arch/x86/include/generated/asm/syscalls_64.h:323
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd8/0x2a0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888104fa4410 of 4 bytes by task 14167 on cpu 1:
copy_fs+0x90/0xf0 kernel/fork.c:1599
copy_process+0xc3f/0x1ef0 kernel/fork.c:2212
kernel_clone+0x16c/0x5c0 kernel/fork.c:2651
__do_sys_clone3 kernel/fork.c:2953 [inline]
__se_sys_clone3+0x1c2/0x200 kernel/fork.c:2932
__x64_sys_clone3+0x31/0x40 kernel/fork.c:2932
x64_sys_call+0x2c0f/0x3000 arch/x86/include/generated/asm/syscalls_64.h:436
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd8/0x2a0 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: 14167 Comm: syz.7.14810 Not tainted syzkaller #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================


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