[moderation] [lsm?] KCSAN: data-race in copy_creds / prepare_creds

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: f83ec76bf285 Linux 6.17-rc6
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17a55762580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6e0c213d0735f5dd
dashboard link: https://syzkaller.appspot.com/bug?extid=82af432ca62af77047d1
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
CC: [linux-...@vger.kernel.org linux-secu...@vger.kernel.org pa...@paul-moore.com ser...@kernel.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e1d8afbdb0f9/disk-f83ec76b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f3464afedb37/vmlinux-f83ec76b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/28905495112a/bzImage-f83ec76b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+82af43...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in copy_creds / prepare_creds

write to 0xffff888104440d68 of 4 bytes by task 24608 on cpu 1:
get_cred_many include/linux/cred.h:202 [inline]
copy_creds+0x78/0x3f0 kernel/cred.c:305
copy_process+0x658/0x2000 kernel/fork.c:2038
kernel_clone+0x16c/0x5c0 kernel/fork.c:2605
__do_sys_clone3 kernel/fork.c:2909 [inline]
__se_sys_clone3+0x1c2/0x200 kernel/fork.c:2888
__x64_sys_clone3+0x31/0x40 kernel/fork.c:2888
x64_sys_call+0x1fc9/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:436
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888104440cc0 of 184 bytes by task 24615 on cpu 0:
prepare_creds+0x6c/0x4c0 kernel/cred.c:219
__do_sys_capset kernel/capability.c:247 [inline]
__se_sys_capset+0x2a3/0x450 kernel/capability.c:216
__x64_sys_capset+0x31/0x40 kernel/capability.c:216
x64_sys_call+0x281f/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:127
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 24615 Comm: syz.2.7492 Tainted: G W syzkaller #0 PREEMPT(voluntary)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
==================================================================


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