[moderation] [lsm?] KCSAN: data-race in copy_creds / prepare_creds (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 7d0a66e4bb90 Linux 6.18
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10bc02b4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=655255e3ef31c19b
dashboard link: https://syzkaller.appspot.com/bug?extid=a9c18b3cb9f026e801ba
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/c1a08104de23/disk-7d0a66e4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6e085d805b84/vmlinux-7d0a66e4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d85572be6ac8/bzImage-7d0a66e4.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a9c18b...@syzkaller.appspotmail.com

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

write to 0xffff888101fd20a8 of 4 bytes by task 13800 on cpu 0:
get_cred_many include/linux/cred.h:202 [inline]
copy_creds+0x78/0x3f0 kernel/cred.c:305
copy_process+0x658/0x2000 kernel/fork.c:2046
kernel_clone+0x16c/0x5c0 kernel/fork.c:2609
__do_sys_clone3 kernel/fork.c:2911 [inline]
__se_sys_clone3+0x1c2/0x200 kernel/fork.c:2890
__x64_sys_clone3+0x31/0x40 kernel/fork.c:2890
x64_sys_call+0x1fc9/0x3000 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 0xffff888101fd2000 of 184 bytes by task 13801 on cpu 1:
prepare_creds+0x6c/0x4c0 kernel/cred.c:219
prepare_exec_creds+0x14/0xe0 kernel/cred.c:261
prepare_bprm_creds fs/exec.c:1364 [inline]
bprm_execve+0x70/0x970 fs/exec.c:1734
do_execveat_common+0x6e6/0x750 fs/exec.c:1860
do_execveat fs/exec.c:1945 [inline]
__do_sys_execveat fs/exec.c:2019 [inline]
__se_sys_execveat fs/exec.c:2013 [inline]
__x64_sys_execveat+0x73/0x90 fs/exec.c:2013
x64_sys_call+0x1fec/0x3000 arch/x86/include/generated/asm/syscalls_64.h:323
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: 1 UID: 0 PID: 13801 Comm: syz.2.3383 Not tainted syzkaller #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
==================================================================


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